You know that what you are doing here is illegal?
The best thing to do here is to contact the site admin again and just tell him the bug. Maybe you can ask more than 0.1btc for that.
The OP is likely trying to pull a cheap scam.
But, assuming there actually was a bug and he's telling the truth, why would that be illegal? If he reported the bug, but the site operator choose to ignore it and do nothing about it - then I'd say he has every legal and moral right to exploit it.
As the OP already said, "
I hahe contact the owner of site and i have explication the question and his offer me 0,1 btc for revelate a bug. For me, is a little amount, because the bug is very big"
The gambling site that OP said is cannot fix it for themselves, so all lose matches will refunded. Lol
SCAM
Newbie account want to try new thing to scam 0.5 BTC with escrow.
I think all gambling sites will manually check and pay their members betting. Refunded the lose bet is perfectly not true. That's why this scammer will not give the gambling site name. "Because he is the owner of the bug site

"