The Black Panthers: Vanguard of the Revolution (2015)
... director Stanley Nelson (Freedom Summer) takes us back 49 years to the beginning of the Black Panther Party, and then walks us through the rise and fall. Rather than the usual textbook approach that focuses on the famous photos of angry black men wearing leather jackets and berets while toting firearms, this is a much more comprehensive look at the complexities of the organization and its members.
It's the interviews with former Black Panther members that provide the most insight. Their stance is that the original plan was a non-violent approach to bring attention to police brutality and the lack of equality in Black America. Many social programs were started to assist kids and the poor, but things turned more aggressive when the passive approach didn't yield the desired results. Newton studied the laws and realized open carry was permitted on public property, and that's where most of the famous photos originated.
The segment on J Edgar Hoover's counterintelligence plan for the FBI to do what was necessary to prevent the expansion of the Black Panthers is one of the film's best. Hoover even described them as "the greatest threat to the internal security of the country" (yes, this was during the Vietnam War). (IMDB David Ferguson)