Anyone have an explanation of this move

I saw this move in Klitschko's video online at 1.39. He does it twice. As far as i can see he blocks the hook and pivots before the right hand. It looks like a very handy move but was wondering if anyone has a detailed breakdown of how it's done, weight transfers, head positiontiong, counters etc.
https://www.youtube.com/watch?v=x1Fd1JLEiaE