"Happy Slapping" the wrong person

I wasn't familiar with "happy slapping" until I encountered a link to this video on the Reddit discussion board this morning. Here is the intro to the Wikipedia explanation:

Happy slapping is a fad in which an unsuspecting victim is attacked while an accomplice records the assault (commonly with a camera phone or a smartphone). The name can refer to many types of violent assaults, not just slapping, but some rape and sexual assaults have been wrongly classified as "happy slapping" by the media. Within the United Kingdon, where the term is used most frequently, it is associated with the ned/chav sub-culture. Happy slapping filming attacks seem to be common in modern bullying, and not unique to happy slapping. The core defining feature of happy slapping is an effort by the attacker to make the assault seem like a comical surprise at the victim's expense. When the "happy slapping" craze first started it was seen amongst youngsters as harmless fun, but as times have progressed some happy slappers have indulged in extreme violence, and several such incidents have had fatal outcomes.

In the video above, the companion of the girl who is happy-slapped is a trained boxer...