Yep, thats the Bungie guys driving it.. specifically Curtis Creamer. It you've listened to the Podcast when they interview Joe Staten about it he claimes that the Hog has several different driving modes because the wheels can all turn independantly, as in it can rotate in place like a tank. It also has 'crab-mode' which allows it to move sideways.
Joe says in Curtis's defense that the vehicle was in crab mode when they gave them the keys, and thus when he started steering it, it turned at the center of the vehicle, not the front wheels like he was expecting.
I should just shutup and link the podcast for anyone who wants to know more.. excellent descriptions of the vehicle:
Bungie Podcast: 09/20/07
http://download.microsoft.com/download/d/8...cast_092007.mp3