Sorry for the quality of this video. I have been having a lot of issues with trying to film this last week and this was the best I could get. I hope I was still able to bring you tingles ^_^
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