Just the video. Taking up your entire window. No stupid comments, no stats, no description, no sidebar.

This userscript takes advantage of YouTube's /embed/ URL, which was intended for embedding videos on websites, but which if accessed as a normal URL conveniently fills the entire window with just the video and none of the sluggish, distracting video page interface.
Example: https://www.youtube.com/embed/jNQXAC9IVRw

Works with all 3 YouTube URL formats: youtube.com / youtu.be / shorts

Notes:

• Rarely, an uploader will disable embedding on a video, meaning that you have to temporarily disable the userscript to view the video.
• The userscript seems to not work when left-clicking links on the homepage (and I'm not sure how to fix it). If you know how, please let me know. You can still always have the userscript work by middle-clicking video links.
• On YouTube search r###lts, you have to leftclick the title of the video (rather than the thumbnail) for the userscript to correctly redirect the URL. Clicking the thumbnail doesn't always trigger it. But this can be treated as a feature, I guess, since it lets you visit the video page normally (in case you need to check the comments) without needing to disable the userscript.