I've found it works best with Youtube, but it actually quit on me not too long ago...I dug into matters a little and found several recommendations of beta 2.055 or something similar, so I downloaded it and was back in business before too long. Only thing is, it no longer goes through Firefox's download manager for some reason, so it's anyone's guess as to when it finishes downloading a video...and it has wigged out a couple of times and left me with an incomplete download. All told, though, when it does work, (and it usually does), it's absolute perfection. I especially love being able to put it in the context menu only. Keep up the good work!