Greasy Fork is available in English.
Adds a MP3 Download button next to the subscribe button, thanks to youtubeinmp3 for their simple download service (http://youtubeinmp3.com/api/). Based off magnus's youtube2mp3 code. Just used something different as it wont open another tab.
hgjk
https://www.youtube.com/watch?v=p8XxGBUjXWc&list=LLyvqgUusvd9Zb3HDCS0OQPA&index=1&t=26s