Guardian: The policing of the G20 protests in London has come under further scrutiny with the release of a video that appears to show at least two instances of unprovoked violence by riot officers against demonstrators. The Independent Police Complaints Commission (IPCC) said last night it was investigating a third instance of potential police misconduct during the demonstrations on 1-2 April after a complaint from a 23-year-old man who says he was assaulted at a police cordon near Cornhill in …