Rights to video footage

My son's classmate made a video of a boy being beaten at the bus stop. He then forwarded it to all his friends. My son sent it to me so I could send it to the parent of the child who was beaten, to the school and the police at their request, and then to the media at the parent's request. Now I am told that I had no "rights" to it and that I could be sued in civil court. Is this correct? Or is it a 1st amendment right?