As far as the trick, it IS a stacked deck, but when the guy cuts, depending on how far he cuts he drives a certain number of blocks (and keeps them in order) until he gets to a set key card, trigger card, and from that he determines how many bars he needs to go into to get to his spot in the deck.
If he is good at counting out his cards in the block it becomes less important for him to switch around the bars, etc, but you get the point.
Ive done card tricks before, its pretty straight forward in this case, no matter where he cuts, you can just shift everything around. You have to pay attention, im sure if he was drunk he would have fugged it up