🎬 Video Preview

If you've ever run a Wan 2.2 upscale chain, you know the drill: you end up with a reference clip, a base pass, and an upscaled pass sitting in three folders, and you bounce between three players trying to spot whether the upscale actually held up. Video Preview (the 🎬 one from Swiss Army Knife) kills that chore. It's a display-only node that shows up to three video files side by side in a custom preview widget, right in the graph.

The name tells you the whole story: no processing, no outputs. You feed it paths and it shows you the clips. reference_vid, base_vid, and upscaled_vid are all optional STRING inputs - wire in whatever combination you have. Drop the reference in the first field and your upscaled result in the third, run the graph, and you get a split view you can scrub instead of a wall of file paths.

How it works under the hood is deliberately boring, which is the point. The node is flagged OUTPUT_NODE, so when it executes it sends the paths you gave it to the pack's JavaScript extension via the standard UI payload mechanism, and the browser renders them. There's no ffmpeg re-encode, no frame extraction, no temp files. That also means the files have to be reachable by ComfyUI's web server - a path on some other machine, or a drive ComfyUI can't serve, will give you an empty widget. No error, just nothing. That's the one gotcha that bites people.

You'll want it in a workflow that already saves videos properly - it's a QA/review node, not a saver, so keep your Save Video nodes in the graph and treat this as the eyeball check at the end. It fits naturally in the Swiss Army Knife style of workflow: a few utils (FilenameGenerator to name the saves, this to compare them) wrapped around a Wan 2.2 pipeline.

Installing

It ships with the whole Swiss Army Knife pack, so install that once:

• ComfyUI Manager: search for "Swiss Army Knife" and install.
• Manually:

cd ComfyUI/custom_nodes
git clone https://github.com/sammykumar/ComfyUI-SwissArmyKnife.git
cd ComfyUI-SwissArmyKnife
pip install -e .

Restart ComfyUI afterward. The preview widget lives in the pack's web directory, so a hard refresh (Ctrl+Shift+R) after upgrading is the usual fix if the widget looks stale.

Troubleshooting

• Blank preview: the file path is the problem 90% of the time. Use paths ComfyUI itself can serve (your output dir, input/, temp/), and make sure the graph actually ran the node that produced the file first.
• Nothing after restart: the JS extension may be cached; hard-refresh the browser.
• Paths with spaces or quotes: keep them plain - the node passes strings through verbatim, so exotic quoting only makes the frontend unhappy.

Is it life-changing? No. But it's the difference between "trust me, the upscale is fine" and actually seeing it next to the source. For a node with basically no moving parts, that's a fair trade.