They use to have old Doctor Who episodes. Not any more. I wanted to see an episode of GoLion (Japanese Voltron) or the Japan version of the Southern Cross arc of Robotech. Can't find 'em. They have all the Robotech Masters episodes, but no Robotech Macross. Oh well.
Ever been to Hulu.com? I can't guarantee that it has what you're looking for, but it's a neat site! http://www.hulu.com
If I miss an ep of something, I'm almost guaranteed it's on BBC i-player... I use YouTube for music videos and funny animal stuff, but not for watching eps of actual programmes...