It's never the content, but the delivery. Same applies to almost all public speakers.
In most cases yes & the Nazi propaganda machine was fully aware of this. No expense was spared to create the right atmosphere at those mass rallies. The whole thing was orchestrated to achieve the desired result which was very much like mass hysteria. Compare that with Winston Churchill's speeches on the radio. Nobody could see him but they wouldn't have had the same effect if spoken by anyone else. He promised nothing but hardship & a long hard struggle. Most of what he was saying was depressing but he succeeded in getting the support he needed from the majority of British people. They're stirring if you listen to them now.
It was suggested here a while ago that some of those famous speeches Churchill made in the House of Commons were later recorded for radio broadcast by an actor impersonating him. I'd not heard of this before then but even if it's true, they wouldn't have had the same effect if not presented in his own unique style.
PS. I can hear him saying it now & quote it almost word for word & I wasn't even born at the time.
"We shall go on to the end, we shall fight in France, we shall fight on the seas and oceans, we shall fight with growing confidence and growing strength in the air, we shall defend our Island, whatever the cost may be, we shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender, and even if, which I do not for a moment believe, this Island or a large part of it were subjugated and starving, then our Empire beyond the seas, armed and guarded by the British Fleet, would carry on the struggle, until, in God's good time, the New World, with all its power and might, steps forth to the rescue and the liberation of the old."
right in there, huh?