I used to speak that fast, and I still do when I forget to speak slow.
The problem is that most humans can hardly follow the speaker and think about it at the same time. I was actually forced to learn to speak slow in high school by my language teacher. My presentations in front of a class were too fast even for the teacher.
Speaking fast has its advantages, but it should only be used for simple presentations like this one. It certainly doesn't work for very scientific topics.
I am not sure of that. I don't have enough evidence to deny nor to accept it.
I remember once another classmate had a presentation and she spoke faster than normal and got criticized for it. However I did not think she was speaking fast until she was criticized. It seemed completely acceptable speed to me and I could very easily follow her line of thought.
This is the only example I remember and it's probably insufficient to accept your conjecture.
Somewhere in the video the neuroscientist talks about her cerebral cortex working differently than it does for most people, and indeed, she's able to understand fast speakers better.
