Bitbet.us is not shutdown by the government or any serious thing that may stop bitbet.us.It is just the domain name expired and the site owner or developer didnt renew or pay for it again because maybe site is not earning a good amount to pay with the domain expenses
I think the owner already posted here above check his post he said their site is under ddos attack that is why the site was down few days ago.. and i think they already fix the issue. the site is now active and i think you can now contact the support which is already posted here check the post above..