Bonus Cash is cash that you can use to wager, but cannot be withdrawn. Any winnings earned from Bonus Cash will be available for withdrawal.
Bonus Cash is only used in wagers once your cash balance has been used. Bonus Cash can be used at the same time as your balance. For instance if you enter a $4.00 wager with a $4.00 balance composed half of Bonus Cash and half of real cash, $2.00 will come out of your cash balance and $2.00 will come out of your Bonus Cash balance. All of your winnings from that match will become withdrawable.