Subscribe and like. I hope this video is ok. I recorded this on my mobile phone and edited on the PowerDirector app. ( I'm not sponsered to say that, just incase any of you wanted to know :) ) :)
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