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!
Basically you'd use the "Get Current Webpage from Safari" block, then in the Terminal
Then add to existing playlist in music. Ah, if only it were legal!