It's about time I recommended a few sites.
First up - The Beatles Video Blog a great source of all kinds of interesting video things.
Here's a collection of (audio) studio outtakes I saw (heard?) on there
You can hear Paul trying to play without a pick (and failing), bossing people about, and being rude in a variety of accents, John Lennon's voice breaking in a variety of songs, and everyone forgetting lyrics...
"you make a bit of wind Doris..."