I don't want to take credit away from this woman. I have an Indonesian friend who cooks with chilli in almost everything but has never tried anything hotter then a birds eye, I gave her an orange habanero to try. After chewing on it for a good minute before swallowing all she says was "very sweet" lol. She was showing no signs of somebody who had just consumed a very hot pepper, I asked if it was hot enough and her reply was "it's ok but not to hot for me".
The northeast part of India consume's more chillies annually then anywhere else on the planet. This area also happens to be where the naga originated from. I guess it's possible over time the woman in the video might have built an exceptional tollerance up to the naga... Goodness knows how many she must have eaten for that to happen though.??
Regarding the receptor in the mouth, I remember reading in the past its an enzyme or similar that activates them and that you can deplete or become tollereny to certain levels of this through frequent exposure.
Just plain crazy putting in her eyes!!! And yes I too wonder how it effects her internally and when all those nagas exit the other end heheh