I had to go way far out of town today to deal with a Post Office issue (ugh), so in my travels, I stopped at three Dollar Tree stores and organized a particular section of the store. Thanks to C O P P A, I can't say what section it was. (Yes, I was wrong about that lavender scented stuff only being at the third one, I know. All those products start to look the same after a while.) Come see the lovely organization! :)
To listen while using other apps, switch the player to Picture-in-Picture (PiP) during playback — it keeps playing in a small floating window (the screen stays on).
To listen with the screen fully off, in-browser playback stops by YouTube's design. Open the video in the YouTube app to keep listening where background playback is supported (e.g. with YouTube Premium).
Open in YouTube app