Interesting, so good and smooth it could appear as if it were a set up/ actor etc? One point springs to mind, dont know if he mentioned it as i could not here the sound so well... but what if they guy got so scared and "in to the senario" that he would have used the rifle (paint gun) butt or head butting and so on, a la the average squaddie in a bar fight, on those actors who were olaying the zombies?? If they had chose some random soldier walking in off duty they would find a few seriously injured actors! But either which way, entertaining clip!
I thought it was quite smoothly done, perhaps too smooth though.
What I did find weird was the reaction of his 'friends' when he zonks out in front of the screen for the first time and a camera crew appear; would you let a complete stranger abduct a friend on a trolley?