In this (fucked-up, not-suitable-for-breakfast-viewing) video, a girl tosses a bunch of puppies in a river. Luckily, the pups are being avenged by the most moral people on the Internet: 4chan users.
According to Gawker, once users of 4chan's /b/ board got wind of the puppy abuser, they set out to find it and punish her. The video was posted to /b/ along with the message "Find this dumb little bitch and throw her into a river" — and users now think they've found her Facebook profile and that of the dude who shot the video. /b/ is mounting a harassment campaign accordingly — because clearly Internet-based vigilante justice meted out by noted assholes is the best way to eliminate cruelty to animals.