This is an old video, but I figured it was about time to re-upload this as a full video and not cut up into pieces. I previously uploaded it in 4 parts, before I was able to post videos longer than 15 minutes. I did also cut out a couple loud seconds that people previously complained about.
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