I just added this to firefox and tested it out. It's working great. DL'd a couple of videos. Wouldn't feel the need if xtube wasn't so damn take down happy. A good video with some cutie in it shows up 2 days later they take it down.

Unfortunately, although it worked very well for a few weeks... the site design must have changed again because the download link doesn't show up anymore! :-(

Now I'm reduced to using Safari's Activity Window.