History of pop in four chords
This was featured on Radio One over the weekend, so I can't take any credit for finding it - but it's very amusing nonetheless: Aussie comedy troupe The Axis Of Awesome deconstruct the "magic" four-chord sequence that underpins all great pop writing (except for Sting, who would add a dminished fifth to show how clever he is, and Status Quo, who haven't learnt the fourth one yet).