🌱 Seedance 2.0 Preview Video URL

Every generation node in this pack returns a video_url - a short-lived link to the clip BytePlus just rendered. Seedance 2.0 Preview Video URL does the obvious, useful thing with it: it downloads that URL into your ComfyUI output folder and plays the mp4 right there in the node, so you can actually watch the result without leaving the canvas.

It's the "sneak peek" node, and it's deliberately lighter than its sibling Seedance 2.0 Save Video. The preview node downloads the clip, shows it, and gives you back the local filepath as a STRING output - but it doesn't load frames into an IMAGE batch, doesn't embed metadata, and has no frame-decoding knobs. It's built for one purpose: confirm the render before you decide what to do with it.

The inputs

• video_url - the URL from any generation node, or from Retrieve Task Result / Generation History Browser.
• save_subfolder - where the download lands inside your ComfyUI output directory, default seedance2_preview.
• filename_prefix - the file name prefix, default seedance2_preview. Files are written as <prefix>_00001.mp4, auto-incrementing so you never overwrite.

Output is the filepath STRING of the saved file.

How it works

It validates the URL starts with http, downloads it in chunks (streaming, so a 4K clip doesn't need to buffer fully in memory), writes it to ComfyUI/output/<save_subfolder>/, and registers it as a preview for the node. If the URL is invalid or the download fails, you get a text error instead of a silent dead node.

Where it sits in the workflow

The practical ordering matters because of the 24-hour expiry that haunts every URL in this pack. The flow people actually run:

Text-to-Video video_url → Preview Video URL   (watch it, decide)
Text-to-Video video_url → Save Video          (keep it, if it's good)

Preview first, save the keepers, delete the rest. Because the preview node writes every clip to disk - including the ones you delete later - it's slightly wasteful on disk if you're previewing a lot of 4K renders. For a quick confirmation loop at 480p it's perfect; for serious archiving, go straight to Save Video.

One honest caveat: because the preview downloads the URL, running it on an expired link fails cleanly with "Invalid URL" - which is also a handy way to discover a URL has already rotted before you try to build on it.

Install: ComfyUI Manager → Install via Git URL → https://github.com/nnnnkatsu/seedance2-comfyui-byteplus, restart. No extra dependencies beyond the pack's own.