Its only $20 i think, but you get it by logging in and the clicking the link on the right and you claim it and its added in 24hrs. Its cashable if you have wagered it 16x, but you could withdraw what you have and give it up a bit like at Bodog, so I would punt it on very long odds to bust over or give it up, OR very very short odds to wager the 16x and cash it.
Just thought i would point this out. the £10 or $20 freebet is not actually a freebet.
If you deposit and bet £10 and then fill in the online form they credit your account with a further £10. The stake is then returned with any bets you place doesnt this make it a deposit match rather than a SNR freebet. so you dont have to search for high odds and can just try to bust to betfair using arbs.
The review like the website suggests its a free bet but in the t&c it says otherwise thought someone might want to alter the review. cheers