Sam Pollard’s “MLK/FBI,” debuts on-demand and in theaters Friday. Pollard, a frequent editor for Spike Lee, examines J. Edgar Hoover and the FBI’s surveillance and harassment of Martin Luther King, Jr. — widely considered one the darkest chapters in FBI history. It’s a murky story dealing with the extramarital affairs of King but, more importantly, about the federal government’s racist attempts to control and thwart the civil rights leader.Regina King’s directorial debut “One Night in Miami” brings Muhammad Ali (Eli Goree), Malcolm X (Kingsley Ben-Adir), Jim Brown (Aldis Hodge), and Sam Cooke (Leslie Odom Jr.) gather into a Miami hotel in February 1964, celebrating Ali’s knockout of Sonny Liston. The set-up, from the play by Kemp Powers (co-director of Pixar’s “Soul”), is fictional, but the dialogue — about power, freedom and Black identity — rings bracingly true. The film, which played at the top festivals in the fall, premieres Friday on Amazon Prime.