Blaming video games, music, and TV have always been easy. Now there's a few cases when shooting happen because the shooter was inspired by a series, a game, or a band, but that's kind of rare. Usually the person will kill a bunch of people and in the aftermath it'll be found out that he loved to play Call of Duty while listening to Slayer and his favorite movies were Ms. 45, Driller Killer, and the Death Wish series (no shade on SpaceTiger that is, I know you love that band and like those films but they're violent as hell).
This. Entertainment has always been a scapegoat so save parents from the scrutiny of their fly by night parenting skills in instances like this.