100% the bikers fault.
Riding over the mountain (they got rid of mad Sunday years ago) during TT week is one of the most frightening things I've done on a bike.
The roads are full of ass*oles who think they can ride. Much like our friend in the video.
In 2012 five people were killed, some of them locals.
Racing was delayed nearly every day and like super del said the evidence could be seen by the markings on the road.
One morning just before mountain mile I saw a black tyre mark and a hole through a grass bank that lead to a 20ft drop from the night before.
It's a tough way to learn that you're not as good as you think you are.