If you win a payout at Video Poker, you can choose to gamble to increase your winnings by clicking on the Double button, which initiates a mini-game, giving you the chance to double your winnings.
The Player wins a round of the Double game: Jack vs 8.
You will be shown a different screen, with no Pay Table, but retaining the Cards and Button Bar sections of the normal Video Poker screen. The card on the left will be face-up, the remaining four cards will be face-down. To play the game, click on any one of the four face-down cards. All four hidden cards will then be revealed, and if the one you selected, which will be marked with a Held flag, is higher than the card on the left, you will have doubled your initial winnings. If on the other hand your card was lower than or equal to the card on the left, you will have lost the payout you just won from the main game, and will be returned to the Video Poker screen, as it was when you left it.
If you successfully double your winnings, you may then try to do so again, by clicking the Double button on the Button Bar and gambling again, or to bank your winnings by clicking the Collect button and returning to the Video Poker screen.
As long as you keep winning, you can keep clicking the Double button, up to the allowed limit. Each time you try to double, the bet is for double or quits; i.e. if you lose, you forfeit everything you have just won, including your original payout from the main game.