In an original special report, MSNBC's Chief Legal Correspondent Ari Melber explores how cell phone videos are advancing police accountability and traces the evolution across policy, politics and technology. The report documents two features of viral police videos that often go "unseen" - the people who record them, and the system's response to the videos, including a backlash that recently went to the highest levels of the FBI. Melber reports on the current climate in the Trump era and the far longer history in the U.S. struggle for civil rights.