Notice how at the very end while Eminem is playing blackjack and there is a 10 and a queen on the table?
It wouldnt be very common for someone to say hit me when they were already at 20.
This is because the odds of getting an Ace, the only card that could allow him to win the game rather than losing it all (from 20 out of 21 mind you) are 1/13.
Any other card and he loses the game.
Then it shows Eminem saying hit me, or making some sort of equal suggestion and another card is thrown and it is the ace.
I think that this is a representation of him naming the album MMLP. If 20 out of 21 was a representation of his career, and 21 was perfect but in order for him to get there he has to risk blowing the whole 20 he has created for himself so far (which would represent his legendary status) he is saying that this album is the ace.