The copy of the short subject I just looked at was not the original version released by Warner Brothers in 1943. It was a revised version issued by the War Office in 1947, which mentioned the Normandy Invasion.
It's a lovingly produced version, set up by Lloyd Nolan, then largely narrated by Paul Lukas, with a one-minute lecture by Felix Bressart on the nonsense of the idea of the Master Race -- before he is dragged off by the Nazis. If you had asked me ten years ago about this movie, I would have dismissed it as full of commonplace truths that we, as a nation, had evolved past. More recent events, including the rise of the alt-right, anti-Black sentiment, and other doctrines of hate, make it, unhappily, timely again.
I disagree with the movie's thesis, that people are not naturally prejudiced. We all grow up in our own little bits of society, dealing with people who look and think and feel like us. People who are not like us require thought and work and we don't always get them right, and when that happens, the results may be bad. Therefore, we approach strangers with caution.
Yet it is those very differences that make other people valuable to us. If we all had the same skills and attitudes, what need would we have for each other? If every man is a farmer, who will make his tools, his clothes, his home? We are stronger because of our diversity.