Danny MacAskill of Inspired Bicycles... got skill

Yes, it's called a freewheel. Try pushing your freewheel bike backwards, the pedals will turn backwards as they only freewheel in one direction. After a 180 he has to let the pedals turn backwards to allow the momentum to carry the bike backwards, otherwise it would just stop.

doh, of course. It was early, what can I say? :-)