Shin Lim's Preferred Handling of the Biddle Trick! A 4-of-a-kind is shown in your hand. The remaining deck of cards is sandwiched between the spectator's palms. One of your cards vanishes and ends up face up in the middle of the pack of cards that they were holding since the very beginning!
While several effects are shown in the trailer, this particular download teaches you this one effect. Others are available for download as well.