2004 was the last year an American teenager could goof off in a school hallway with zero chance a stranger would ever see it. Facebook had launched that February, locked to Harvard students. YouTube was still a year away. The first iPhone was three years out, and nobody carried a camera that talked to the internet. So when a camcorder came out, kids hammed for it, because the tape had exactly one destination. A drawer in somebody's parents' house. Maybe a screening at graduation, then twenty…