If you are of a sensitive disposition I advise you never to watch this film.
They have used this film as a teaching aid in French schools for many years...
Alain Resnais' film encapsulates the horror of the concentration camps by juxtaposing b&w footage of 'inmates' to modern photography of Auschwitz and Majdanek as they stand today.
There is content here that they do not tell you in textbooks. It makes you sick to your stomach how certain plans could ever have been dreamed of, never mind even put into action.
There's footage of Himmler and his cronies nonchalantly perusing diagrams for the gas chambers, calmly discussing how effectively they can eliminate thousands of people.
And there's stills of the victim's themselves, and how they were hence turned to ash via the enormous ovens which showered the camps with a snow-like dusty film.