The video is at Real Clear Politics. Watch it and decide for yourself. I think he has done this too often for it to have an innocent explanation. It’s his trademark now. He did it to Hillary quite clearly, and the audience laughter made clear that they understood it. He did it to McCain during the campaign. There are other times when he’s done it. I think he did give the GOP the finger, and that makes him an adolescent in an adult’s body. It shows his utter disrespect for anyone he perceives to be his enemy, and that is a long list.