Edit a previously generated video with a text prompt and optional reference images (video-to-video). Pass the video `url` you received from `createVideo`, `createVideoFromReferences`, or an earlier edit — it must be a video you generated within the last 7 days; arbitrary external videos are not accepted. Optionally add up to 5 reference `images` (URL or base64) to guide the edit. Synchronous: the call blocks until rendering finishes and returns the new video URL and its actual duration in seconds. Credits are charged only on success, based on the produced duration and never more than the duration you requested. Pass an optional `request_id` to tag the result so you can locate it later via `getVideoResults`. Related tools: `createVideo` to generate the source clip, `createVideoFromReferences` for reference-driven generation. Requires an API key (user scope).