Target fixation was a factor, and trying to keep up with the rider ahead of him and use that rider for his 'line' was another factor. Notice how sloppy his turns got when he tried to catch up to the rider ahead.
The camera is pointing in the center of his line of sight. In the crash corner, at first he's looking up the road at the bike ahead. Even at the 3:33 mark the camera is still lined up on the bike. Two seconds later the lead bike has moved significantly to the left onscreen as he moves to the right edge of the lane. Then he seems to fixate on the big yellow < sign. Once he focused on that he was done. I'll bet as he got closer to the armco, his grip became viselike and his arms were basically locked up. No matter how hard he pushed to get the bike to turn (if he even did that), his opposing arm fought the input. It's a simple and very common panic reflex, and it's not easy to overcome that reaction.