I was looking around and i found a better way to rip sounds off youtube videos, i havent tried it on all of them, and it also takes longer (DL's the whole MP4 off youtube)
add this to bookmarks
javascript:if(document.location.href.match(/http:\/\/[a-zA-Z\.]*youtube\.com\/watch/)){document.location.href='
http://www.youtube.com/get_video?fmt='+(isHDAvailable?'22':'18')+'&video_id='+swfArgs['video_id']+'&t='+swfArgs['t']}
and go to the youtube site with the vid you want, and click the bookmark, it should download a MP4 file.
PS. This is also an easier way to get vids that you want off youtube.