A Bonus Bet will enable you to place bets without risking your own Cash and is non-withdrawable. If you make winnings from the bet placed with a Bonus Bet, that will be added to your Cash balance.
Returns will be of the value of your winnings, and not include the stake. For example, a bet placed with $25 Bonus Bet stake at $2 odds will return $50 - $25 = $25.