A few commands are listed below for reference on use of Youtube-DL, which is operated via terminal / bash (installed via homebrew on Mac).

% youtube-dl -F 'https://taibbi.substack.com/p/rachel-maddows-shocking-new-low-4a6'

That will show the available downloads where you an then use the following command

$ youtube-dl -f <pick the numbered option> 'youtube.address'

% youtube-dl -f 140 'https://youtu.be/W8v4wxy9xpU'

That will download the available .m4a file.