After watching this demo, I have to agree with scribble, minjae, and xerenix. This guy appears to be just really good at pub. I checked out his steam profile and his all of his screenshots, except one, is with him on the leaderboard. He's got over 2k hours logged which I'm assuming is spent playing pub. If he was hacking, he would have been banned a long time ago via vac.

NOW ONWARD TO ARTHUR!