I did an edit of my recent mason jar water sounds video! These are two different mason jars that I was testing. Let me know if you have a favorite or like a mixture of both, like I did here!
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