This isn't a direct answer to your question, but it's a noteworthy tangent. One factor that made Hitler an effective speaker earlier in his career was that he was one of the first politicians to make extensive use of air travel. In his 1932 Presidential campaign, he flew roughly 30,000 miles and spoke at almost 200 engagements. His campaign slogan was, in fact, "Hitler über Deutschland" - "Hitler Over Germany". This allowed him to make full use of his charismatic speech style in person, giving him an advantage over opponents. This doesn't directly address the specific methods of his speech, but it does show that Hitler was savvy enough to know how and when to best utilize his abilities while campaigning to achieve the results he wanted.

Source: "Rite of Spring: The Great War and the Birth of the Modern Age", by Modris Eksteins

The guy was a natural, he knew how to feel a crowd and what to say to move it. He also had a very distinctive way to speak, rolling the Rs (which is never done in German) and speaking with a very specific rythm.

A German friend once told me that for German speakers the way this guy talked is both fascinating to the point to be almost hypnotic and quite ridiculous at the same time.