Footage leaked from “Call of Duty: Modern Warfare 2” reveals that players of the upcoming video game can shoot innocent civilians in an airport in a realistic rendering of a terrorist attack. The game, which has an “M” rating for mature audiences, comes out next month in what its publisher hopes may be the most lucrative launch in the history of entertainment, not just for games but counting music and movies too. In a statement, game publisher Activision Blizzard said Wednesday the footage was taken illegally.