Preview Video

ComfyUI finally speaks native VIDEO as a first-class type, and the nodes have caught up. You get Save Video for keeping files, and you get... nothing for just looking at one. That's the hole Preview Video fills: it's the "preview image" of the video world. Feed it a VIDEO, get a playable preview right in the node, and - the part that makes it worth installing - nothing lands in your output directory.

Why does that matter? If you iterate on LTX, Wan, or any video model, you're generating over and over while you hunt for the seed, prompt, or step count that doesn't look like wet clay. Every one of those runs going through Save Video piles a hundred .mp4s into your output folder that you'll never watch again. Preview Video writes to ComfyUI's temp directory instead, which ComfyUI already cleans up for you. It's a genuinely small quality-of-life win that you'll feel the first time you actually look at what's accumulating in output.

How it works

The mechanism is boring in the best way. It takes your VIDEO, encodes a preview copy to the temp folder with the same automatic container/codec behavior as Save Video, and hands the original video straight through its output so you can keep wiring it downstream. It's an output node, so it can execute a preview branch on its own - you don't need Save Video hanging around just to look at something.

The one clever bit is metadata. With include_workflow_metadata on (the default), it embeds the workflow into the preview using the same comment-atom format Video Helper Suite (VHS) reads. Right-click the preview, Save video, then drag that file back into ComfyUI and the whole graph reconstructs. Same "workflow included" culture that images have had for years, now for video - but it needs VHS installed to read it back.

The inputs that matter

Most of the time you touch exactly two of them:

• format - container for the temp preview. Leave it on auto and it matches Save Video's behavior.
• codec - auto passes the video through as-is. Only pick h264 with the re-encode option when you want a specific crf (default 23, lower = better quality = more temp disk). Auto is faster and preserves your file as generated.

The others are set-and-forget. include_workflow_metadata is on by default. filename defaults to ComfyUI_preview and supports ComfyUI's text replacements - try preview_%date:yyyy-MM-dd% - with a counter and extension appended so repeated previews never overwrite each other. It's also the suggested name when you save from the preview menu. Below the video you get a compact info line: resolution, frame count, fps, duration.

The only output is video, the unchanged original. Wire it into whatever comes next.

Installing it

ComfyUI Manager, search Preview Video, install, restart. Or the manual way:

cd ComfyUI/custom_nodes
git clone https://github.com/elgalardi/ComfyUI-PreviewVideo.git

Restart and search "Preview Video" in the node library. No model downloads, and despite importing PyAV under the hood, there are zero third-party dependencies - av already ships inside ComfyUI, so this won't start a dependency war in your environment. That's rare and worth appreciating.

Where people get burned

The big one: this needs ComfyUI 0.30.0 or newer, because it uses the versioned V3 backend API. If the node won't load or your manager-compatible version is behind, that's the reason - update ComfyUI first.

Second, temp files are temp files. They're eligible for ComfyUI's normal temp cleanup, so don't point anything long-term at them. The workflow metadata only embeds when you save through the preview menu - a preview left in the temp folder is just a throwaway look. And if you're on a video workflow that ends in Save Video anyway, this node buys you nothing; it's for the iteration loop, not the final export.