David stalls the deck a little and tells snoop to see a card, that stalling is 4 of spades which david knows before hand so he uses a marker and writes that card's name before the trick and surprises every1, its all about creating a scene.
David stalls the shuffle just a little, i.e he is deliberately convincing the viewer to see the black queen did u notice that watch again thats the trick !
he reads the oponent very effectively which others lack alot