IDK why'd you even bother with legal, it's easy enough to rip mp3s out of any youtube video.
these are in my ~/.zshrc:
# download any video as mp3
# if video is chaptered, split each chapter into separate song files
alias yt-mp3='yt-dlp --extract-audio --audio-format mp3 --split-chapters --no-check-certificate'
Download everything that would upset you if it were no longer available forever starting tomorrow.