He's referring to the artificial restriction that wouldn't allow the game to run at all if you had less than 6GB of RAM, despite the game only really using 2GB at most. The game was patched a while ago to remove that restriction. I think CoD Ghosts runs off of Steam exclusively on PC, so Steam should have automatically update the game for you. If it didn't, right click on Call of Duty Ghosts, click on properties, and under the updates tab, select, 'always keep this game up to date'