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Black Forest Labs' FLUX 3 Draft Extend Video continues an existing clip into a fast 720p preview from a written brief, built for cheap continuation trials before a full-quality pass. Trading expensive final-quality reruns for quick extend checks while keeping a reusable draft cache for later enhancement, FLUX 3 Draft Extend Video helps marketers, editors, and previz artists iterate without burning budget. For developers, FLUX 3 Draft Extend Video on RunComfy can be used both in the browser and via an HTTP API, so you don't need to host or scale the model yourself.
Ideal for: Clip Continuation Drafts | Low-Cost Extend Tests | Storyboard Tail Previews
This page covers the extend-video draft endpoint in the FLUX 3 family. You provide a source MP4 and describe how the shot should continue; the model returns a quick 720p continuation so you can validate the next beat without paying full FLUX 3 Extend Video rates.
The endpoint is built for the early loop of editorial work: continuation prompt tests, duration trials, and batch draft extends. When a take looks right, reuse the returned draft cache with draft-enhance for a fuller finish.
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FLUX 3 Draft Extend Video continues an existing MP4 into a fast 720p preview from a written brief. It fits continuation trials, editorial tail tests, and high-volume draft extends where cost matters more than final sharpness.
Both continue from a source clip; FLUX 3 Draft Extend Video returns a cheaper 720p preview plus a reusable draft cache, while the full endpoint is better for polished 720p or 1080p deliverables.
FLUX 3 Draft Extend Video requires a prompt and a source video URL (MP4, at most 50 MiB). Duration can be auto or 5–20 seconds, with aspect ratios auto, 21:9, 2:1, 16:9, 4:3, 1:1, 3:4, and 9:16.
Along with the preview clip, FLUX 3 Draft Extend Video returns a reusable draft cache you can pass to draft-enhance for a fuller-quality render without rebuilding the continuation from scratch.
No. FLUX 3 Draft Extend Video is video-to-video: the source clip anchors the final frames, and the prompt guides how the shot continues. For still-driven drafts, use other FLUX 3 draft modes.
Yes. Prototype in the RunComfy model UI, then call the same FLUX 3 Draft Extend Video template through the RunComfy API with matching parameters. Generations consume usd / credits on both paths.
FLUX 3 Draft Extend Video is billed at $0.132 per second of generated draft video at 720p. A 5-second continuation costs about $0.66; longer outputs scale with the generated length.
Stay on FLUX 3 Draft Extend Video for continuation drafts and early editorial reviews. Move to full FLUX 3 Extend Video or draft-enhance when you need sharper finals for ads or client delivery.
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