This script expects some tools to be installed on your PATH, namely:
Call mp3.bat to download a video URL as mp3 into your Music folder.
Either pass a URL, e.g.
mp3.bat https://www.youtube.com/watch?v=yKf9aUIxdb4
or just call
mp3.bat
without arguments, in which case the URL is read from the clipboard.
The mp3 files will be saved into your Music folder.