This is probably the worst play sand in the world... and this is what I get for buying play sand in the dollar section. I bought some much better play sand after this and am going to re-do this video later on.
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