The YouTube to mp3 userscript generates a "Download" button on any "YouTube watch page". Convert from YouTube in high quality mp3 and download the file directly to your device. The Youtube Converter userscript works with Tampermonkey, Violentmonkey, Greasemonkey and other user script manager.
Thanks to:

https://www.rcyoutube.com/
https://conv2.be/
https://www.youtube.com/