I hope you enjoy this video. I don't think all of this video is inaudible. If there is a better way for me to do inaudible whispering that I could do in another video for you, you can let me know in the comment section of this video :)
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