Two versions are explained: one with a special watch and one other for the impromptu situations.
The performer removes their watch and asks a participant to twist the knob to move the hands around randomly. The performer's head is turned away the entire time. When the participant is happy, he looks at the watch and remembers the random time he stopped at. For example 8.45
Then, the spectator deals the cards and stops whenever he wants. So, three bills are placed in the deck in order to select three cards randomly.
Now, let's go to the effects...
The performer divine the chosen time: 8.45.
The three chosen cards are one 8, one 4 and one 5...
Each bill reveals a perfect prediction of each card: 8 of HEART, 4 of SPADE and 5 of CLUBS.
The deck is turned face up... All the cards are blank !
To emphasize the idea that the participant didn't actually see anything, the performer asks her to look again at the watch she holds. The hands on the watch are gone.
Everything is examinable and reset in seconds.