Amid the chaos in Lower Manhattan on Friday morning as the Occupy Wall Street protesters marched through the streets, there were two encounters between protesters and the police that were captured, however imperfectly, on video and then ricocheted across the Internet...The associate legal director of the New York Civil Liberties Union, Christopher Dunn, said that the white-shirted officer’s actions seemed unwarranted. “This was a chaotic situation and we don’t know what happened earlier in the sequence,” Mr. Dunn said, “but it’s hard to imagine a justification for the roundhouse swing shown on the tape.”