Super PiP is a browser extension which allows you to watch videos in Picture-in-Picture mode. A menu bar of playback controls will show up so you can:
If the Youtube video has subtitles, a window of subtitles will also show up together with the playback controls.
Please reload all existing tabs after installation. So you can see playback controls. New tabs will work automatically.
This extension works on all streaming websites including Disney+, Hulu, Youtube, Netflix, etc.