I'd suggest reading up on the rise the Bolsheviks in Russia and Mao in China if you want to have some context for what these people are talking about. The Great Courses offers some great lectures on both subjects.
Because that's some regularly overlooked context to the rise of Hitler, with his brand of fascism focused on anti-Bolshevik/communist sentiments which neatly played into racial theories [1] and stereotypes [2] that were rather common back then.
[0] https://en.wikipedia.org/wiki/Bavarian_Soviet_Republic