The latest release from the archives of one of the popular late-night ’70s shows proves that “The Midnight Special” was nothing if not catholic. The TV concert program straddled AM and FM; hit records were the one requirement for the acts chosen. Barry Manilow and the purveyors of “Disco Duck” were onboard, yet there were inspired segments, including Van Morrison backed by George Benson, Carlos Santana, Etta James and Dr. John on “Moondance.”