A holocaust documentary about unreleased Alfred Hitchcock footage of the liberation of Nazi concentration camps aired in 15 countries Monday, as part of the international Holocaust Remembrance Day commemorations. HBO’s “Night Will Fall” includes harrowing footage captured by the legendary filmmaker, who recorded the grim scene that met Allied troops at Bergen-Belsen, Dachau and Auschwitz in the spring of 1945. Initially, Hitchcock together with media baron Sidney Bernstein were commissioned by the British government to make “German Concentration Camps Factual Survey,” a documentary that was intended to show Germans the horrors of Nazi brutality.