The part towards the end, where he does the actual climb of El Capitan in Yosemite National Park, is also worth watching.
Amazing guy. The National Geographic documentary had Hollywood-esque layers that slightly annoyed me (ominous music etc), though. A documentary by Werner Herzog about Alex Honnold would be fascinating; something in the vein of his 1974 "The Great Ecstasy of Woodcarver Steiner" [1,2]. I would have loved to see more of the philosophical, introspective side of Alex Honnold in the NG movie. In case of Herzog's ski jumper Walter Steiner, it was very much there.
0: https://www.youtube.com/watch?v=tnRoda7Ke2w
1: https://en.wikipedia.org/wiki/The_Great_Ecstasy_of_Woodcarve...
2: Full movie here: https://www.youtube.com/watch?v=oTdQ2fGlrq8
I'm very skeptical of that claim. It seems just as reasonable that he has a perfectly normal brain that is exactly as afraid of things as the rest of ours, but he's spent a lot of time doing terrifying things and has learned to suppress how his body reacts to it.
you can find his brain scans and see that his visual to amygdala connecting path is activated significantly less than for normal people (which in other words is "much less afraid of danger"). It is a question though whether it is a result of training or an original anatomy.
He doesn't behave the same, where normal climbers would freak out and do a fatal mistake he repeatedly remains calm as on sunday tea party. You can train some resistance to fear of death and indeed all climbers do (myself included), but almost everybody hits some wall within their current skills. His wall is way further than almost any other climber. Not that he is the only soloist, far from it.
The only abnormal thing about his brain scan was that his amygdala activated less than usual when he looked at frightening or disturbing images, which would be entirely compatible with deliberate desensitization (perhaps through ~20 years of practicing climbing with no protection?)
What I didn't expect was that he died on a non-solo climb he was doing, while descending, in an avalanche. Which is the same risk any high-altitude alpinist takes.
Given his incredibly rigorous training and laborious and meticulous preparation (years!) for the ascent beforehand, what looks like risk to us is probably as much experience to him. The connections to his amygdala don't seem to have had impact on rational thinking.