Thiis 1978 film was conceived and written by Eric Idle (who also starred) and produced with a little help from Lorne Michaels. It aired way back when on NBC and the BBC. Guest stars include (but are not limited to) George Harrison, Mick Jagger, Paul Simon, Dan Ackroyd, Bill Murray, John Belushi, Gilda Radner and Michael Palin. Not only is it funny as hell, but many of the songs are of true Beatle quality. I've been listening to the original soundtrack album ever since.
This YouTube playlist will take you through the entire film, which runs about an hour and fifteen minutes.
Your Overlooked Film headquarters is Sweet Freedom