Tomorrow Belongs to Me - Cabaret
https://www.youtube.com/watch?v=_tUctFu46_c
The patriotic song from Cabaret, in the beergarten in pre-war Nazi Germany, sung by the arian Hitler youth. You see many young and old people getting taken up by the song, but you can also see the old man who remembers WWI and knows what will happen.
The “Hitler Youth” were formed *after* the Nazis took power, not before or during their rise to power.
The old guy is too old to be remembering WWI, which was only about 10 years before the events of Cabaret, with disgust and cynicism for the German Nationalist sentiment of the song. Perhaps he is supposed to be thinking back to the German Romantic Movement in the 1880’s. He would have been young then, and would remember the idealism of that time, and how it led to the German Imperialism of the 1890’s and early 1900’s.