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FLUX 3 Video Extend: AI Video Editor

Continue any video clip with prompt-guided motion and native audio using FLUX 3 Video Extend by Black Forest Labs. Try free — pay per generation. FLUX 3 Video Extend continues an existing video clip with prompt-guided motion, scene development, and camera movement — with optional native synchronized audio — using Black Forest Labs' unified image/video/audio architecture. Source clips must be under 50 MB and under 15 seconds.

Interactive model controls

FLUX 3 Video Extend continues an existing video clip with prompt-guided motion, scene development, and camera movement — with optional native synchronized audio — using Black Forest Labs' unified image/video/audio architecture. Source clips must be under 50 MB and under 15 seconds.

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Overview

About this model

FLUX 3 Video Extend continues an existing video clip with prompt-guided motion, scene development, and camera movement — with optional native synchronized audio — using Black Forest Labs' unified image/video/audio architecture. It's the way to chain FLUX 3 Text to Video or FLUX 3 Image to Video outputs into longer sequences, or continue any existing MP4 clip under 50 MB and 15 seconds. Once extended, run the result through FLUX 3 Video Upscaler for a higher-resolution final pass.

1Sequential Storytelling: Chain multiple FLUX 3 Video clips into one continuous scene.
2Shot Extension: Add a few extra seconds of motion to an existing clip without re-shooting.
3Continuity Testing: Preview how a scene develops before committing to a longer render.
4Social Media: Extend a short clip to fill a longer format slot.
5Iterative Editing: Refine the direction of a shot by extending it with new prompt guidance.
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Pricing & Value

Cost analysis

muapiapp$0.25/sec (720p), $0.42/sec (1080p)

Pay-per-generation pricing, no subscription required. Audio generation included at no extra charge.

Fal.aiNot available

FLUX 3 Video Extend is not yet listed on Fal.ai.

ReplicateNot available

FLUX 3 Video Extend is not yet listed on Replicate.

** Competitor pricing is estimated based on similar model architectures and usage tiers.

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Technical Details

Configuration schema

Promptstring

Text prompt describing how the video should continue.

Default ValueThe camera pulls back to reveal a sunrise breaking over the skyline, birds taking flight.
Video URLstring

URL of the source video to extend. Must be under 50 MB and under 15 seconds.

Default Valuehttps://d3adwkbyhxyrtq.cloudfront.net/webassets/videomodels/flux-3-video.mp4
Aspect RatioEnum (6 options)

Aspect ratio of the output video.

Default Value16:9
Durationint

Length of the extension in seconds.

Default Value5
ResolutionEnum (2 options)

Output video resolution.

Default Value720p
Generate Audioboolean

Whether to generate synchronized native audio for the extended video.

Default Valuetrue
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Implementation Guide

Developer documentation

How to Use FLUX 3 Video Extend

  1. Provide a source video — an MP4 under 50 MB and under 15 seconds, via video_url.

  2. Write a continuation prompt — describe the next action, scene development, camera movement, mood, lighting, and visual continuity.

  3. Configure output — set resolution (720p or 1080p) and duration (5–20 seconds) for the extension.

  4. Toggle generate_audio for synchronized native audio on the extended portion, at no extra charge.

  5. Submit the request:

curl -X POST https://api.muapi.ai/api/v1/flux-3-video-extend \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"prompt": "The camera pulls back to reveal a sunrise breaking over the skyline", "video_url": "https://example.com/clip.mp4", "resolution": "1080p", "duration": 5, "generate_audio": true}'
  1. Poll /api/v1/predictions/{request_id}/result until completed.
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Common Questions

Frequently asked

What is FLUX 3 Video Extend?

It continues an existing video clip with new prompt-guided motion and scene development, using Black Forest Labs' unified image/video/audio architecture.

What are the source video requirements?

The source clip must be an MP4 under 50 MB and under 15 seconds long.

Does the extension keep native audio?

Yes, synchronized native audio for the extended portion can be toggled with `generate_audio` at no extra charge.

How long can an extension be?

5 to 20 seconds, billed rounded up to the next whole second.

How much does FLUX 3 Video Extend cost?

Muapi bills $0.25/second at 720p and $0.42/second at 1080p for the extended portion, rounded up to the next whole second, capped at 20 seconds.

Can I chain multiple extensions together?

Yes — feed the output of one extension back in as the `video_url` of the next call to keep building a longer sequence.