AI Video Extender

Upload a clip that stops before it should, say what happens next, and get a longer version that carries on from where your footage ends. The continuation inherits the last frame, so the subject, the light and the camera move stay the same rather than restarting as something new.

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How to extend a video

Upload the clip you want to continue
A shot you generated earlier or a piece of footage you filmed, chosen as a file from your machine. Short clips are what this is built for. A couple of seconds at the low end, around fifteen at the top. The tool reads the end of what you give it, so the last second matters far more than the first.
Describe what happens next
Not what the clip already shows. What should follow it. "She turns towards the window and the light catches her face" is something a model can act on. Leaving the box empty asks it to guess, and the guess is almost always more of the same at the same speed.
Choose how many seconds to add
The duration control runs from two to ten seconds. Short additions hold together more reliably, because the model has to invent less than it can see. Ten seconds of new material from a three-second source is a large ask; three seconds is a small one.
Pick a model and generate
Different video models handle continuation differently. Some hold a character steadily, some are built for length, some come back quickly. Extending is not instant; expect to wait through the generation rather than watch it appear.
Check the join, then keep going
Play the seam at full speed before you judge it. The result lands in your library, where you can cut it against other shots or add voiceover and captions to finish the piece. If it still runs short, the extended clip can go back through the tool as the next source, provided it is inside the accepted length.

What people use it for

The generated shot that ends too early

Most video models return a few seconds. When the shot is right but the clip runs out before the beat does, extending keeps the take you already approved, rather than regenerating from scratch and hoping the second attempt lands the same way as the first.

Holding a shot under narration

A line of voiceover takes as long as it takes. If the picture runs eight seconds and the sentence runs twelve, extending the shot is far less obvious than freezing it, and much less obvious than looping it.

Filling a fixed slot

Ad placements, pre-roll and platform-native formats all come with a length. Extending lets you meet the slot without recutting the whole edit around footage that came in short.

B-roll that needs to breathe

Faceless and documentary-style channels live on establishing shots. Two extra seconds on a landscape or an interior is the difference between a cut that lands and one that feels rushed.

Rescuing footage you cannot reshoot

Something you filmed once, at an event that is over, where the camera stopped a moment too soon. You cannot go back for a longer take, but you can continue the one you have.

Ambient and background loops

Rain on a window, a fire, traffic at night. Backgrounds for streams, storefront screens and title cards need to run far longer than any single generation, and extension is how you get there without a visible restart.

What is AI video extension?

AI video extension continues an existing clip. You give the model a video you already have, and it generates additional frames that plausibly follow the ones you gave it, for a length you choose. Same subject, same setting, same direction of travel.

The important part is where it starts. The model conditions on the end of your footage, so the final frame of your clip is effectively the first frame of the new material. This is the same idea as image-to-video, which uses a still as its first frame, except the model also sees motion: how fast things were moving, which way the camera was going, what was about to enter the shot.

That is what separates extension from simply generating a second clip. A fresh generation, even from a near-identical prompt, invents its own version of the scene. The face shifts, the light changes, the room is subtly not the same room. Extension is constrained by what already exists, which is a limitation and the entire point.

It is worth being clear about what it does not do. Extension adds to the end of a clip; it is not slow motion, not a freeze frame, and not a loop. The added seconds are new content, generated once and fixed thereafter, and they carry the same probabilistic quality as any other generation. You may want two or three attempts before one continues the shot the way you had in mind.

Extending a clip vs generating a new one

The obvious alternative to extending is to generate again and ask for a longer clip, or to generate a second clip and cut the two together. Which one is right depends on a single question: does the new footage need to be the same shot, or only the same scene?

Sometimes it has to be the same shot. Continuous, unbroken, no cut. Extension is the only approach that gets you there. Two generations placed end to end will not match. Faces drift, clothing details change, the wall behind the subject picks up a different texture, and the join announces itself immediately. Audiences are unforgiving about continuity in a way they are not about most other flaws, precisely because it is the kind of error that never happens in real footage.

If it only needs to be the same scene, a cut is often the better answer, and less work besides. Two angles on the same subject, joined at a sensible moment, will read as deliberate filmmaking. A long unbroken take is a stylistic choice, not a default, and reaching for extension every time a clip feels short produces videos that drift rather than move. When you want length and do not need continuity, generating a second shot from a different angle gives you an edit instead of a stretch.

The third option is the editing timeline: slow the clip down, hold on a freeze, or loop it. These have their uses, and none of them asks a model for anything. But slowing footage below a certain point makes the motion look wrong, a freeze reads as a deliberate device rather than a continuation, and a loop is visible the moment anything in the frame moves at a steady pace. A walking figure, drifting smoke, a pan. Extension is the option that keeps the shot behaving like a shot.

There is also a sequencing argument. Because extension continues from what exists, it rewards getting the first few seconds right before you add to them. Generating a short clip, judging it, and then extending the one you like is a more controllable process than asking for the full length up front and discarding the whole thing when the middle goes astray. Short first, then longer, is the workflow that wastes the least.

Getting better results

End on stable motion
The model extrapolates from the final moments of your clip. If those moments are a whip pan, a hard cut, a flash of motion blur or a fade to black, it has ambiguous information to build on and the continuation wanders. A source that ends mid-movement at a steady speed is much easier to continue.
Write forwards, not backwards
The prompt describes the future, not the past. Restating what the clip already showed tends to produce a repeat of it. Say what enters, what turns, where the camera goes next. One concrete change, phrased in the order it should happen.
Add in short steps
Three seconds twice usually beats six seconds once. Each pass lets you check the result before committing to more, and because each extension conditions on the previous one, a good short addition becomes a good foundation. A long single jump has more room to drift and nowhere to correct.
Keep one thing moving
A continuation that has to sustain a camera move, a subject action and a lighting change at once is being asked to invent three things simultaneously. Pick the one that carries the moment and let the rest hold steady. It is also how the shot would have been directed in the first place.
Trim the source before you extend
If your clip ends on a wobble, a dropped frame or an accidental extra beat, cut that off first. You are handing the model a starting point, and a clean starting point is worth more than a longer one. This applies doubly to footage that has been through heavy compression.
Judge the seam at full speed, then in a loop
Scrubbing frame by frame will always show you a join, and it will make a perfectly good extension look broken. Watch it play, at normal speed, the way a viewer will. Then loop the two seconds either side of the join. If nothing pulls your eye, it works.
Treat sound as a separate layer
Do not rely on audio surviving a generation. Build the picture first, get the length right, then lay voiceover, music and captions over the finished cut in the editor. It is easier to write narration to a known duration than to extend a shot to fit a line you have already recorded.
Generate more than once
The same clip and the same prompt will not give you the same continuation twice. Two or three attempts give you something to choose between, which is a better position than accepting the first result because it is the only one you have. Vary one thing between runs. The duration, or a single clause of the prompt. Then you learn something from the difference rather than just rolling again.

The video models

Veo 3.1 — Google's photoreal generation, with sound. Up to 12 seconds.
Kling 3 — Cinematic motion that holds a character across a cut.
Seedance 2.0 — ByteDance, up to 24 seconds. The long shots.
Grok Video — xAI. The fast one, when you want to see something quickly.

Questions

How much longer can I make a video?: Each extension adds between two and ten seconds, chosen before you generate. To go further, run the result back through the tool as a new source. It has to sit inside the accepted length, so trim the earlier part off first. Every pass after the first builds on generated material rather than your original footage, which is why quality holds up better over a few short steps than over many long ones.
Which model should I pick?: The picker inside the tool is the authority: it loads the video models that support extending, and that list can change. Broadly, pick for the thing the shot needs. Steady character continuity, a longer take, or a quick look at whether the idea works at all. Re-run the same source through a second model when the first continuation is close but not right. The source and the prompt matter more than the choice of model in most cases.
What length of clip can I upload?: Short ones. A source of a couple of seconds up to around fifteen is the working range. If you have a long piece of footage and only want to continue the end of it, trim it down first. The model reads the final moments, so the rest is not doing much for you anyway.
Will the extension match the original exactly?: It continues from the last frame, so the subject, setting and camera direction carry over, which is the reason to extend rather than regenerate. It is still generated material: fine detail can shift, and complex textures or crowds are where a difference is most likely to show. Watching the join at full speed is the honest test.
Can I extend footage I filmed myself?: Yes. The tool does not care whether the source was generated or shot on a camera, as long as it is within the length range. Filmed footage often extends well, because real motion is consistent and gives the model unambiguous information about what was happening.
Does it work on any kind of shot?: It works best on shots with steady, readable motion. A walk, a pan, a slow push, a landscape with movement in it. Rapid cuts, heavy motion blur, dense crowds and text on screen are harder, because there is more to reconstruct and any error is more visible.
What about the audio?: Plan on building sound separately. Voiceover, music and captions are added in the editor once the picture is the length you want, which is the more controllable order anyway. You can write to a known duration instead of stretching a shot to fit a recording.
Why did my extension drift away from the shot?: Usually one of three things: the source ended on unstable motion, the added duration was long relative to the source, or the prompt described the scene rather than what happens next. Trim the end, ask for fewer seconds, and give one concrete action to perform.
Can I use the result commercially?: What you make is yours. Check the terms for the specifics before you build a campaign on it, and make sure you have the rights to the source footage you extended.