One day in 1969 while filming a mural across from the Black Panther Party’s Boston office in Roxbury, I was approached by three black youths. The mural depicted an egg cracking open and giving birth to a Black Panther—I thought they were coming to congratulate me for my interest in it.

Instead, a member of the group informed me that they were appropriating the movie camera “for the community.” When I refused to hand it to them I was punched and pushed to the ground. My first encounter with the P…