That is our family rule: If you fight over it, then we (mommy and daddy) will take it away. This is mostly why our kids don't play video games often, or for a long time. One or the other will inevitably start to whine. I am ruthless when this happens - I immediately turn the TV off or take the electronic game away. My son used to think that when he stopped whining, I would allow him to continue playing. Well, he quickly learned that once the privilege was lost, it was GONE, sometimes for the rest of the week.
Consequently, when I see them enjoying a video game, I wonder how long the peace will last. Today, however, it seems that they finally got it all figured out...let's hope it lasts!