Correct me if I'm wrong, in order to complete the tasks and earned with this affiliate program, you and each user you've referred must complete an offer which is like this
"To complete this offer simply sign up to Betfair, deposit £10 and bet through the entire amount.
Cost: £10.00"
And I guess no one tried that so there's no one get the .25 btc of this site.
You should be right after all I comment that I read. I didn't enter the site but all from comment and the way that he wants to complete the offer, it should be like you said.
Did you find out if he paid. The offer seems to good to be truth and most of the time it means the owners will run away without payout.
I don't want to be a victim of such a scheme.