Extend Video With AI: Make Any Clip Longer With MiniMax H3 Max Extend

MiniMax H3 Max Extend is an AI video extender on Flixly: you upload a clip, describe what happens next, and it adds 5 to 15 seconds of new footage that picks up exactly where your clip ends. Open Extend Video in Flixly Video Tools to make a clip longer.

Great shots often end too soon. A drone pass stops just before the reveal, a product spin cuts off halfway, or a scene you generated needs a few more seconds before the next cut. H3 Max Extend continues the clip you already have instead of starting over, keeping the same subject, look and camera.

See H3 Max Extend in action

This is the clip we started from: 5 seconds made with MiniMax H3 Max on Flixly.

And this is the same clip after one extension with H3 Max Extend (5 seconds of new footage, 768p, Full video). The first five seconds are the original; everything after is new, and it continues the same fox, light and camera move. Both are shown unedited apart from web compression, with the sound the model generated.

The prompt for the extension:

The fox reaches the top of the hill, stops, and sits down in the wet grass. It turns its head to look out over the misty valley as the sun rises and warm light spreads across the scene. The camera slowly rises behind it.

What is H3 Max Extend?

H3 Max is MiniMax's post-trained H3 video model, and H3 Max Extend is the version built to continue an existing video. It takes your clip as the starting point and generates new footage that follows from its last frame and from your prompt. You choose how much to add, how sharp it should be, and whether you want the whole video back or only the new part.

New to H3 Max itself? The H3 Max hub post covers the base model.

H3 Max Extend at a glance

How to extend a video with AI

1. Open Extend Video in Flixly Video Tools.
2. Upload a clip between 2 and 60 seconds long.
3. Under What happens next, describe the continuation: the action, where the camera goes, and how the scene changes.
4. Pick how many seconds of new footage to add, from 5 to 15.
5. Choose a resolution: 480p for quick drafts, 768p or 1080p for most work, 2K for the sharpest result.
6. Keep Same as my video for the aspect ratio, or crop to another shape.
7. Choose Full video to get one file with your clip and the extension, or New footage only to get just the continuation.
8. Check the estimate and generate.

How to write a prompt for a video extension

The model already sees your clip, so the prompt only needs to say what happens next. Describe the continuation, not the original.

• Start from the last moment. If your clip ends with a runner reaching the top of the stairs, write what the runner does at the top, not how they got there.
• Name one clear action. "She turns toward the window and smiles" extends more cleanly than a list of five events.
• Say where the camera goes. "The camera keeps pushing in slowly" or "the camera pans left to reveal the harbour" keeps the motion continuous.
• Keep the world consistent. Mention the same time of day, weather and setting your clip shows, unless the change is the point.
• Let short extensions breathe. Five seconds fits one beat. Save bigger changes for a 10- or 15-second extension, or extend twice.

Example prompts:

The fox reaches the top of the hill, stops, and looks out over the valley as the sun comes up. The camera slowly rises behind it.

The skateboarder lands the trick, rolls toward the camera and raises both arms. The camera stays low and tracks backward.

The product keeps turning on the pedestal until the logo faces the camera, then the lights dim to a soft glow.

Full video or new footage only?

Full video returns your original clip followed by the new footage as one file, ready to post. New footage only returns just the continuation. Pick it when you want to edit the join yourself, add a transition, or chain several extensions in a video editor.

Tips for smooth extensions

• End your source on a steady moment. A clip that ends mid-whip-pan or mid-cut gives the model less to continue from.
• Trim first. A shorter clip that ends at the moment you want to continue is cheaper to extend and keeps the extension focused.
• Draft small, then scale up. Try the prompt at 480p and 5 seconds, then generate the take you like at 1080p or 2K.
• Chain extensions. Download the result, upload it again, and extend once more to build a longer shot.
• Upscale at the end. For 4K delivery, run the finished clip through the Video Upscaler.

What it costs

You pay for the seconds of new footage at the resolution you choose, plus an amount that grows with the length of the clip you upload. Shorter source clips cost less to extend. Flixly shows the estimated price before you generate, and the final charge uses your clip's exact length.

Try it

H3 Max Extend is live in Extend Video. Need a clip to start from? Make one with MiniMax H3 Max in the Video Generator, then come back and extend it.