Just me doing a practice run of my speech, repeating myself over and over, just getting you and the neighbors phone starts ringing lol. Sorry this is late I got that distracted with comments and messages yesterday I forgot to post.
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