It is a crack up, I think it is all tongue and cheeck, that is how I seen it anyways. Take for e.g. when they are being interviewed and are asked questions about their songs they just ask stupid questions back.
The pie thing is so unbelievably random, it's funny. You're watching a DVD with a concert from the greatest band every to walk this Earth, and instead you get the drummer saying he doesn't like crust on his pie :D