Reload the page when you get that "no longer available" message. I've had this happen frequently on my computer lately as well, but when I reload the page the video is there. Not sure what's up with that. Of course, there are times when the error message is legitimate and the video really has been pulled.
Does not work, i've sent a message to Youtube, let's that they'll answer something else than they are no longer available to correct this problem.