Short film made by the US Army just after the Second World War, warning about the tactics that Nazis use to gain power by dividing minorities from each other and telling blatant lies.

This video has subtitles in English, you can see them by clicking the CC button.

More info (by the way the Wikipedia page has the wrong year, this film is from 1947):
https://en.wikipedia.org/wiki/Don't_Be_a_Sucker