FLUX.3 Extend Video Draft by Black Forest Labs is the fast, low-cost preview mode for video extension: continue an existing clip from its final frames and generate a quick draft, with native synchronized audio, to preview what happens next before committing. Feed a source video under 15 seconds, then re-render the draft at full quality on FLUX.3 Extend Video, keeping the same subjects, composition and motion. Supports 5 to 20 seconds in aspect ratios from 21:9 to 9:16. Ideal for trying continuation ideas fast.