How to Do a "mentalism" card trick

The magician starts off by saying he will not complete the trick on camera because it is not for up-close viewing. There is a link to go watch the trick being performed. This is a mind reading-prediction trick. There are two decks of cards, red and blue. The viewer is asked to choose one deck. The magician takes the cards of out that deck and pulls a card from the middle. This is the prediction card. Then he puts the rest of the cards back in the box and removes those cards. He takes the cards out of the remaining deck and tells the viewer to stop him while he's counting them. However, he has removed the top card from this deck and placed it on the box for the cards so that it blends in. He had the cards already set up so that the top card on each deck would correspond with a card in the middle, so he knew what card he was looking for. Then when the viewer says stop, he makes it look like he is slamming that card down, but in reality he is picking up the one on top of the box. He flips both cards over and they match!