DISCLAIMER: This is not intended to be informational or construed as advice regarding real estate transactions of any kind. (Seriously. All the forms were obtained at random using Google image searches. Don't trust a lady with a two-tiered shelf as a desk to give you decent home-buying advice. It's clearly a fly-by-night operation.)
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