Inside America’s ‘militias’ – from the KKK to the Oath Keepers

America's self-styled militias have roots dating back to the KKK's formation during Reconstruction. In the latest "Reality Check with John Avlon: Extremist Beat," CNN's Sara Sidner joins Avlon as they trace this history, from the Minutemen of the 1960's to the deadly Oklahoma City bombing to today's Oath Keepers.