“The average homosexual, if there be such, is promiscuous. He is not interested in, nor capable of, a lasting relationship like that of a heterosexual marriage.”

So declared Mike Wallace in authoritative voice-of-God tones in “The Homosexuals,” a tawdry, sensationalist 1966 “CBS Reports,” excerpted in Kate Davis and David Heilbroner’s valuable film, “Stonewall Uprising.” Funny how yesterday’s conventional wisdom can become today’s embarrassment.

The most thorough documentary exploration of the three days of unrest beginning June 28, 1969, when patrons of the Stonewall Inn, a seedy Mafia-operated gay bar in Greenwich Village, turned on the police after a routine raid, “Stonewall Uprising” methodically ticks off the forms of oppression visited on gays and lesbians in the days before the gay rights movement....