It is common for bitcoin sites to move to manual withdrawal in cases where there are some security reasons to check for withdrawal requests manually one by one.
However, keeping it manual is not a good sign, since it prolongs the trust users needs to give to them, which is by no measure fair.
I would never deal with a betting site while my withdrawals are questioned or prolonged w/o a good reason..
Can you tell me what are the security checks which a site does before allowing withdrawals? A person deposits, bets on a sporting event, wins the bet if he's lucky and then he has to wait for hours to receive his withdrawal? I don't like this one bit, especially when we're talking about bitcoins, the withdrawals should be instant, if they're manual then the site should ensure to finish the pending withdrawals every 2 hours.
But I suppose this must be mentioned in their terms, that they do manual withdrawals which may take this much time. Read the terms next time OP and/or choose the sites which offer instant withdrawals.