For those times when you don’t need the video and just want to listen to the audio later, add this snippet to your toolbox. To use, copy the URL to your clipboard, then expand the snippet in your command line. Prerequisites: Homebrew, youtube-dl, and ffmpeg.

youtube-dl -f bestaudio [clipboard] --exec "ffmpeg -i {} -codec:a libmp3lame -qscale:a 0 {}.mp3 && rm {} "