Video: Footage of reveller flung to the ground by police during Sydney Mardi Gras sparks police brutality claims

A video showing a police officer standing on an unidentified young man's back, pinning him to the ground with his foot.
One onlooker in the video can be heard to exclaim "We just saw you whack his head against the ground. His blood is on the ground."

Witnesses at the event and YouTube viewers have called for an investigation into the policeman's restraining actions.
Sydney MP Alex Greenwich said: "I'll be calling for an investigation. From what we can see it does appear to be heavy handed and extremely concerning."

YouTube uploader 'SydneyMardiGras2013', who claims to have been a press photographer at the event aledges in the video description that a police officer "..grabbed him by the back of the neck and slammed his head into the stone pavement, as he tried to get up he was then punched multiple times in the head, leaving blood all over the pavement. The crowd of people overlooking screaming at the officer to stop."