I'm guessing the documentaries don't dwell on those speeches for a long time, right?

It's hard to show just one excerpt from a speech that is potentially an hour-or-so long without context. The speeches need to be summarized because you wouldn't be able to glean what they're talking about just from listening to a few minutes.

Here's Hitler's speech about Stalingrad:

https://en.wikisource.org/wiki/Adolf_Hitler%27s_Stalingrad_Speech

You'll see it's kind of all-over-the-place and choosing just a few lines from it to summarize is hard. In this speech, he talks about his own life, his coming to power, he compares bolshevism to communism in Wiemar Germany, he talks about previous German military successes, and so on. Picking a few lines from this speech to summarize it is very hard.