Scene extension versus regenerating the take

Do not extend a bad hook. Do not regen a good plate to "make it longer."

Extension continues. Regeneration resets. Those are different verbs, and they cost different things. Extend when the last frame is good and the next beat belongs to the same shot. Regen when the idea is wrong — the open failed, the face is not the face, the room is not the room.

The Flux-shaped version of this fork is Flux 3 Extend versus a new generate. This page is the production rule that holds across extend-capable models, including Veo 3.1, whose live extend call is a fixed 7-second beat, not a duration slider.

What each button actually does

Extend takes a clip you already have and generates what happens next from its last state. On Veo, that is a 7-second continuation per call; chain them if you must, with a fresh prompt each time. On Flux 3 Extend, it is a continuation of the source video and its audio, which is why the room tone does not recast. The input is a take. The output is more of that take.

Regen is a new generate from the same brief (or a rewritten one). New noise. New face, unless a still or a reference pinned it. New room tone. The take you liked is gone. You may get a cousin. You will not get the same shot, longer.

People reach for regen to add duration because "longer" lives in the duration dropdown and extend lives behind a second model. That is how a good 8-second plate becomes a different 12-second plate, and the 8 seconds you had approved are now an anecdote.

The last-frame test

Before you spend, look at the last frame. Not the whole clip. The last frame.

If you would print that frame — identity, light, product, mouth, hands — extend. Prompt only the next beat. Do not re-describe the person. Do not re-lit the room. The frame is the brief now.

If you would not print that frame — motion blur, a blink, a melted label, a hook that already lost the viewer — do not extend. Extending a bad last frame is how a small error becomes the ground truth for the next 7 seconds. Regen the take, or regen from a locked still, or cut.

If the first two seconds are the problem, extend cannot help you. Extension cannot rewrite the open. A bad hook with a pretty tail is still a bad hook. Regen the open, or replace it with a hook you generated as its own object. Extending a miss is how you pay twice for a clip nobody held.

Last frame	First seconds	Move
Printable	Holding	Extend. Prompt the next action only.
Printable	Dead	Do not extend. Replace the open. Keep the tail only if you can cut to it.
Unprintable	Holding	Regen, or recut so you never hand off from garbage.
Unprintable	Dead	Regen the idea. The take is not a plate.
Printable, but the idea is wrong (wrong room, wrong claim)	Either	Regen. Extension will faithfully continue the wrong idea.

Duration is not a reason to regen

The second-most expensive habit: a good 8-second Veo take, a brief that wanted 15, a new 8-second generate with "same scene, a bit longer" in the prompt.

You did not make it longer. You recast it. If the 8 seconds are good, extend them. Veo's extend is 7 seconds per call; two calls off a keeper is how you get ~15–22 seconds of that shot. If 22 seconds is still not enough, you probably wanted a second shot, not a longer first one. That is the 30-second single pass versus stitched 8-second decision, not a regen.

Flux 3 Extend is priced as a continuation, not as a cheap pad — higher than a fresh Flux 3 text-to-video generate on purpose. Read that price as a warning: extend is for a take worth keeping. If the take is not worth keeping, a new generate is the cheaper honesty.

What to write in an extend prompt

Describe the next sentence of the shot, as if the camera never cut.

• Do: "She turns to the sink and rinses the bottle, same kitchen window, same overcast."
• Do not: "A woman in a sunlit kitchen with a blue bottle…" — that is a regen prompt wearing an extend button.
• Do: match camera height and light to the last frame.
• Do not: "now a drone shot of the house." That is a new setup. Generate it as a new shot.

Veo extend also takes a negative prompt. Use it to keep an artefact from continuing: extra fingers, a drifting label, invented text. Do not use it to invent a new scene.

One extend pass is the move. Chaining extend off extend is how drift compounds where you are least likely to watch — the audio bed, the jacket, the product angle. If the sequence needs another room, cut.

Hooks, specifically

A hook is a first-frame object. Extension is a last-frame object. They do not treat the same disease.

If the hook failed, regenerate the hook (or pull a different one from a pack). Extending a hook that did not hold gives you a longer clip of a miss. If the hook held and the body ran out of shot, extend the body, or cut to a still-locked I2V continuation — not a new T2V that restages the open.

FAQ

Can I extend a clip that did not come from the same model?

Depends on the endpoint. Flux 3 Extend takes an MP4 under its file limits; it does not require the source to be Flux. Grok Imagine Extend only continues its own task IDs — an uploaded stranger is rejected. Veo extend is a Veo continuation. Read the input contract. "Extend" is not one API.

How many times can I extend before I should cut?

Treat one continuation as the default, two as a push, three as a smell. Each pass is conditioned on the previous pass's ending, not on your original plate. If you are extending because you wanted a new beat in a new place, you wanted a new shot.

The take is good except for one moment in the middle. Extend or regen?

Neither. That is a retake of a segment, not a continuation past the end. Tools like LTX 2.3 Retake exist for "remove the man / fix seconds 3–5." Extending cannot reach backward. Regen throws away the seconds that already worked.

Is a longer duration slider on a new generate the same as extend?

No. A duration slider on a new generate re-imagines the whole clip at a new length. The shot you liked is an input to nobody. Extend is the tool that has that shot as an input. If the plate is good, use the tool that can see it.