There is a new - official -
Monty Python channel on YouTube.
It features high-quality clips from the
Flying Circus series, their various movies, and TV specials. It also includes some original material - including (so far) new interviews with Eric Idle and John Cleese.
In case you're looking for a good starting point, I've always considered
this one of the funniest sketches ever. (Too bad the TV version doesn't have a proper ending).