I like how his first concern was not about his friends getting shot, but just to get as much footage as possible! How sick is that?
Be careful to get the timeline absolutely correct Anons! Sounds to me like he was there at the school during the day. He was filming in the closet at around 9:30am (prior to the shooting, during the drill); he then went home after the shooting, then rode his bike back to the school to get more footage.