A video that appears to show a Champaign police officer using excessive force has been posted anonymously on YouTube.  The police dash-cam shows an officer confronting a man, grabbing his arm, spraying him with mace and later placing his hands around the man's neck.  The arrest took place last June.  A previous investigation determined the officer acted within police standards but Champaign City officials say a new investigation is warranted.  There's no word on who is responsible for posting the video on the Internet.