Yeah. BTW, on macOS, it would be trivial to hack together an Automator workflow that gives you a Service (ie, a menu item in Safari->Services) that says "Download Video", or "Add Youtube Song to Music", and does what it says.

Basically you'd use the "Get Current Webpage from Safari" block, then in the Terminal

  PATH="/usr/local/bin:${PATH}"
  cd Music/YTDownloads  
  # or wherever you want it
  youtube-dl -q -f 140 "${@%%&*}"  
  # format 140 is 128k .m4a

Then add to existing playlist in music. Ah, if only it were legal!