How to Perform the "tell the truth" card trick

This video shows you a mind-reading card trick. This particular trick requires 8 cards: 4 kings and 4 queens. First, the subject is asked to memorize one of the 8 cards as they are laid out before the subject, face-side up. The cards are picked up and sorted in various ways and the subject is asked a series of questions. The questions are always asking whether the card the subject memorized is in a certain group that the trick performer presents. The card in question always is in the group the performer presents. The cards are then divided into 2 piles. The cards act like a lie-detector test. The subject can choose how to respond when asked questions by the performer, but the cards will know whether they are lying or telling the truth. The first question is asked using the first pile of cards and the subject is revealed to have lied. The bottom card on the pile is a queen and the person said they choose a king. Those cards are set aside. The remaining cards are then split again and another question is asked to determine the color of the card. The subject says black, but the bottom card is red, so the subject has lied again. Again, the remaining cards are split and the final question is asked to determine what suit the card was. The subject says it was a diamond. The card is flipped over and reveals a diamond, so the subject was telling the truth this time. The performer then deduces that the card the subject choose was the queen of diamonds. He successfully reveals the final card and it turns out to be the queen of diamonds. The video ends with the performer telling the viewers that they can watch the tutorial on how the trick is done in a subsequent video.