Watched most of the coverage. Those guys are crazy and very fast. Many of the top guys had been doing this for years and competed in all the 2-wheel classes. Side car had their own races.
It appeared that the top racers were Pro TT racers, where the TT was their primary or only major race. A number of other competitors were various amateurs. It seemed to be really competitive you had to dedicate yourself to learning the 37 mile course and finding the fastest lines through each corner. Not something a person can do in a week.
It did make for some great video.