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.
Firefox Greasymonkey Download error 'COuld not parse script
"Could not parse script:
Ignoring @match pattern http*://youtube.com/* because:
Error: @match: Could not parse pattern."