It is one of the most useful and frequently used sleights used in magic tricks and is well worth devoting some practice time to, until you can do the move as smoothly as possible.
Effect : The spectator "freely" chooses a card from the pack. They then press their chosen card tightly between their hands. The magician waves another card over the spectators closed hands and the two cards miraculously change places ???
Like David Blaine you can improvise your patter to add some atmosphere and excitement to the trick.
As mentioned in the video, you can personalise the trick to your own style if you wish, by varying the way that you perform the double lift or by the choice of the three cards that you use.
Most of all, the trick is a lot of fun to perform. Wait till you see the reactions on your audiences face as they try to figure it out.