Upvote:2
In terms of Allied propaganda being a root cause of the German revolution, I'd say Hitler's statement is not accurate. I'd further state that Mein Kampf is a political/ideological document, and any historical references in such documents should be immediately suspect.
Ultimately, failure of an authoritarian ruling class in Germany had led to defeat on the battlefield and starvation/deprivation at home. This was the proximate cause of the revolution, as it had become clear to the general population of Germany as 1918 waned that the grand stalemate on the Western front had been broken and that defeat of the Central Powers was inevitable. Allied propaganda was not necessary. The troops marching back towards Germany every day could see what was happening, as could the hungry civilians behind the lines. The population was moved to change governments, and the only way to do this in an authoritarian system is through revolution.
See for example http://www.markedbyteachers.com/gcse/history/why-was-there-a-german-revolution-in-1918-and-how-far-had-it-gone-by-1919.html