By making the two seemingly futile bets, you can now get your free bet from the bookmaker without ever having to risk with your funds. Now you have basically made yourself income in the form of a free bet.
To protect their revenue, bookies will not allow you to withdraw this money immediately. You will be asked to place another bet with the bonus stake to be able to get it. Now you've got two options. Of course, the bonus can be used to to place a bet on a horse or player that you think is going to win and hope for the best. After all, that's free money you're gambling with so you cannot lose your own funds...
Despite that, I strongly urge you to use a more lucrative option of utilising bonuses. If you do matched betting for the second time and place bets with both the sportsbook and Betfair
betting exchange, you can convert the free bet into a risk-free revenue regardless of which player or dog wins! It's a more lucrative way to utilise your free bets and your returns are more regular and more predictable.