Its more the player then the video game i would think. You have to look at the activity and what it brings about really. When it comes down to it, its a competition. To see who is better, just like in any sport. You try and take away a football stars practice time or make him miss a game and he will flip on you! like wise with your bother, if you try and take away his playing time he snaps!
He needs to find a sense of reality, I support video games, they keep kids at home, away from drugs and drinking. but there is a point they are taken to far, and its when you start living in the game world, when you lose the sense of your world around you. That is when you start seeing problems.
He is not lost, he just needs to see that his life should not be about video games. There is help out there, but its going to be hard to tell him otherwise, just because the games today feel so real, and create that false sense of reality.
Take World of Warcraft for instance. You can talk with other people, see their in game person, engage in anything you want with them. For example you can drink beer with them, go fight them, fight along side with them, Do anything with them in this false world. And it becomes comfortable for them to be there, and think this way. That is why your losing him.
Once he can become comfortable again in the real world, only then will he come back from this state he is in now.