Night and Fog (1955)

Sometimes classified under the decree known as "Nacht und Nebel," "night and fog"
Marked with two large Capital Ns.
Political prisoners wearing the red triangle meet those wearing the green triangle: common criminals, masters in the ranks.
At the top, the Kapo, almost always a common criminal.
Higher up yet: the SS, the untouchables, to be addressed from ten feet away.
At the top, the Commandant, who oversees the camp routine. He pretends to know nothing of the camp.

Night and Fog represents the peak of director Alain Resnais' activities as a short-subject filmmaker. Framed as a documentary, the film is an unsettling view of life inside the Nazi concentration camps of World War II. As he would in his later features (Hiroshima Mon Amour, Last Year at Marienbad et. al.) Resnais toys with chronology, with memory becoming present reality and vice versa at several critical junctures. Jean Cayrol, later responsible for the script of Resnais' Muriel (1962), wrote the narration for Night and Fog. The film was originally released in France as Nuit et Brouillard. ~ Hal Erickson, All Movie Guide

Running Time: 31 mins
Night and Fog (1955)

As this review show, it is a short documentary film. In addition to filming the empty concentration camps there was a lot of use of archived film the Nazis had filmed and notably some shots of the Nazis in parade from the film Triumph of the Will. And a short interview with Alain Resnais of about 5 minutes long.
This film does a good job describing the Kapos and the privileges they get.

Cleanliness is health.
Work is freedom.
To each his due.
A louse means death.