Firstly, it is not illegal to bet on offshore Online sites for US residents including the New Yorkers. And the site mybookie claims to be a Costa Rica based operator.
Let me clear you mybookie is not a regulated sports site not even in pro-gambling States like Nevada, New Jersey, and Delaware. It does not possess a license to operate in any of those 3 States.
But NY residents can open account at mybookie and no one stop you to gamble at this online gambling site.
Here, in New York you can choose SportsBetting, BetOnline, 5Dimes as your top three online sportsbook options.