In the video, the player switches his cards to create a winning hand.
Sometimes there will be one player that does the switching, while another player distracts the dealer.
For example, as the dealer is focused on 1st base, the 3rd base player will use this time to look at both his cards. Watch how he brings one card from his 2nd hand over to his 1st hand and then slides his other card towards his 2nd hand. He completed the switch without the dealer noticing.