In the hopes that people will stop messaging me about this issue, I'm correcting a grave mistake that I made in yesterday's cursive video. I hope you can forgive me for it someday. (And if people would stop messaging me about it, that'd be awesome.)
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