Can anyone give me the lowdown on his picking technique here? I love the style but I play electric mostly and generally only strum or fingerpick when I play acoustic so I'm new to this type of syncopated acoustic picking. His right hand is going a bit too fast for me to get it just by sight.

At the start I can see him slapping and picking with his thumb and then his other 3 fingers but it seems like he's getting other sounds out of it some how, kind of hard to explain. And wtf is going on at 4:18, is he tremelo picking with his thumb?? Anyone got insight or a link to help out?
He's using some sort of travis picking and slapping the strings with his own, to me "weird", righthand technique. Check out Just Sandercoe's lesson on it, it's great. He explains how to play it like John Mayer plays it and other ways of playing the same thing but with different fingerings as well http://www.youtube.com/watch?v=z6oDmSANUOg