She's not addicted to video games. She has ADD, and needs something that is quick and easy to keep her stimulated, and video games fit that bill. Just when she starts playing its hard to get her to stop. I know she doesn't want to waste the time she has with real people, but I understand how easy it is to go "just another 5 minutes" over and over again.
It used to be, in her mind, that "if they care about me they'll let me do anything I want" and she thought they would stick around waiting for her to get done, but she has long since realized other peoples' schedule can't revolve around her.
If she has something else to keep her sufficiently stimulated, and if she isn't playing them when she has to start something else, video games aren't a problem at all.
As far as "her mother talking" thing is concerned, the only thing you can't say is "I need you to..." or "You need to...". Nothing else hits the trigger. It doesn't matter who says it, she'll get angry. Her mom always told her that she needs to do this, she needs to do that, etc., and she hated it.
She does realize her temper negatively affects her life. She still has a short a fuse as before, and still gets just as angry, but she calms down much faster than she once did. However, it doesn't take long for the damage to be done. I don't do anything to baby her on it, and in fact I don't tolerate it. At the climax of her anger the only thing she'll respond to is someone that won't back down.