The weird thing is we should be able to know! I recall at one point one of the incidents was investigated, and they said that under hard braking at high speeds, particularly sustained hard braking, certain chemical changes happen in the surface of the brake pad due to the temps. They said they found no evidence of those chemical signs.
Brake fluid absorbs moisture from the air and it's boiling poing reduces over time, making it more likley that heavy braking will boil the fluid and kill the brakes.
This happened to a friend of mine driving through the rocky mountains in Canada; brake system overheated and he had no breaking ability until it cooled down.
This is a great comment, however I just want to add some context. Brakes likely had nothing to do with this incident. The problem was a worn/damaged axle bearings.
The RWD thing is definitely important here. Given that the majority of cars and a significant number of SUVs are now FWD, this doesn't hold water. Given it is the front brakes that are more powerful than the rears, and if your brakes are maybe a tad worn out, you might not be able to take your brakes from a dynamic friction situation to a static friction situation. In the mean time, your engine would just continue injecting heat into the brakes, which could easily overcome them. It might also be that he was not braking with the full force initially, meaning some degree of heat saturation may have already been present.
The brake pads and jaws get contaminated with dust and the like,making them stick a little. My guess is they get disassembled before test and cleaned perfectly.
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