A tipster helped cops identify a 17-year-old boy accused of slapping a Jewish man and knocking the yarmulke off his head in an anti-Semitic attack in Brooklyn last week, cops said Thursday. The suspect, whose name wasn’t released because of his age, approached the 22-year-old victim on Avenue L near New York Ave. in Flatlands late last Friday, cops said. Video shows trying to intimidate the victim, then slapping him in the face, knocking off his yarmulke. Advertisement Surveillance video shows Jewish man get slapped while walking in Brooklyn street during random attack. Authorities also released additional video of the...