Just tried the site, and the half a dozen bets I made did checkout in the provably fair system. You can view the "server seed" by double-clicking on the bet-id of the previous bets you made.
But it looks like a really stupid system. There's no absolutely no reason they should be changing the server-seed each bet (makes it so difficult to be impractical to verify a bunch of bets). And the way the system is now, the nonce serves no purpose at all (other than also complicating verification). But it does appear to be give you enough to verify your bets, if you go through an impractical ceremony.
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But then it hit me!
They can actually check if you're going through the impractical ceremony on not! I verified this by checking the network requests, and AFAICT the only way to view the server-seed hash is via a network request to "/ajax/modal" with "modal=fairness".
So this means they can actually if you're verifying the bets or not. So they could trivially cheat only when they know you won't be able to tell (when you never requested the server-seed hash).
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So I'm going to agree with the OP on this one: the site doesn't meet standards expected of a provably fair site.
Quoting, to re-read later.