I'm going for B at fault here. I was going to go for racing incident, but on replaying the video, i watched driver b's incar shot again, and you can clearly see driver a is IN FRONT of driver b at the corner without even having to use the look buttons, yet he still turns in sharply.
there wasn't even a question of whether "a" got his nose up to the a pillar of "B" of anything, "a" had half his car in front of "b".
and you gotta love those conversations after that dont ya?