Much clucking behind television anchor desks follows the airing of popular internet footage of girl fights. After repeated displays of adolescent girls slapping each other, pulling hair, and ripping off clothes, news anchors wonder out loud about the reasons for their popularity among YouTube and other internet viewers. It’s no big secret: This is a genre of pornography. The occasional tough-girl fight on school grounds that one came across with flinching embarrassment is now captured by a video camera for the titillation of millions of sick viewers. The violence factor and the authenticity of the fight are the draws that...