A young man strides purposefully into the woods as a cameraman asks what he's about to do. "About to go beat up this bum," the man in the video says. And that's exactly what he does, punching and kicking a homeless man in the face, bloodying his nose, before wishing him a Merry Christmas. The videotaped assault has led to criminal charges against a 20-year-old New Jersey man and a 17-year-old boy accused of filming the assault while egging the attacker on. "Just dive on him! Dive on him!" the cameraman says on the video as the assailant approaches a...