📹👁 Video Preview

ComfyUI's core Preview Image node is great for stills and useless for video - you get a filmstrip of frames, not a playable clip. Video Preview fills that specific gap: drop it at the end of a video pipeline and it renders an actual inline video player right in the node, so you can check your result before you commit to a real export step.

It's part of justUmen's Bjornulf_custom_nodes pack, and specifically the video-tooling corner of it, alongside things like Images to Video, Video details, and the various ffmpeg conversion nodes. This one is purely a display node - no output - you look at it, you don't wire anything from it.

How it works

It's dual-mode, which is the useful bit: you can feed it either a video_path pointing at an already-rendered file on disk, or an IMAGES list straight out of your pipeline (say, right after VAE Decode on a video-diffusion workflow, before you've bothered saving anything). If you go the IMAGES route, fps_for_IMAGES tells the node what playback speed to render the frames at, since raw frames don't carry their own fps the way a video file does - a file fed via video_path already knows its own fps, so that setting only matters for the frame-list path.

The inputs and outputs that matter

• video_path (optional) - path to an existing video file to preview.
• IMAGES (optional, IMAGE type) - a frame list to preview directly, skipping the need to export a file first.
• fps_for_IMAGES (default 24, range 1–60) - playback speed when previewing from a raw frame list.
• autoplay (default false) - start playing immediately when the node renders.
• mute (default true) - muted by default, mostly because browsers are picky about autoplaying unmuted media; flip it off if you want audio and aren't autoplaying.
• loop (default false) - loop playback.

There are no outputs - this is flagged as an output/terminal node, the video equivalent of Preview Image. It's meant to be a dead end you look at, not something you keep chaining.

How to install it

ComfyUI Manager: search "Bjornulf_custom_nodes," install, restart. Or:

cd ComfyUI/custom_nodes
git clone https://github.com/justUmen/Bjornulf_custom_nodes

then restart ComfyUI. Playing back from video_path needs the same ffmpeg tooling the rest of the video nodes rely on; previewing straight from an IMAGES list doesn't need ffmpeg at all, since it's rendering the frames the browser can already handle. The pack's requirements.txt covers opencv-python, ffmpeg-python, and friends - install with pip install -r requirements.txt from inside the custom node folder (ideally in a venv on Linux, or via python_embeded\python.exe on Windows portable).

Common issues & troubleshooting

Nothing shows up when using video_path. Check the path is correct and absolute - there's no file browser here, and a bad path just leaves you staring at an empty node with no obvious error. This is the same class of issue as the pack's other video nodes: they lean on real files existing at real paths, not on ComfyUI's usual input/output folder conventions.

Video plays but has no sound even though you expect it to. mute defaults to true - that's deliberate, not a bug, since browsers commonly block autoplay of unmuted media and this avoids that failure mode by default. Turn it off manually if you want audio.

Trying to preview a video pack you haven't actually rendered yet. If you're feeding IMAGES straight from a sampler, remember this node is playback-only - it doesn't save anything to disk. If you like what you see, you still need one of the pack's save/convert nodes (or ComfyUI's own save-video functionality) to actually persist the result.

Because Bjornulf's video nodes were built and mainly tested on Linux per the README, Windows users hitting odd playback issues here are running into a known rough edge, not something uniquely wrong with their setup.