There is no internet (let alone social media or body cams) during that era, since Jim Crow in America was still being enforced towards black people at that time, but the civil rights movement is gaining traction (since Martin Luther King was alive). I mean, cop violence has been around for a long time before body cams were invented. How did people hear first hand encounters from those victimized back then without reliance on social media?
News travelled at lightning speed through the telegraphic poles, see! A modern miracle, see! Faster than a printing press drawn by a score of horses. You won’t believe it until you see it. Bet your bottom dollar!