How can i help my little brother with his video game addiction?

He plays as soon as he gets home from school. When he goes to a friend's house, he plays the game, what his friends told me. He curses people out unprovoked with his friends for what he says is "fun." He stays up to 11 pm playing the same game to.COD BO and MW2. How do i help him without being too brash or looking like a bully. I want to help him without it making it look like i'm mocking him.