He was going under 50. I consider that to be a pretty easy pace for that kind of road.
He WAS being pretty cavalier about staying in his lane. But it actually almost looks like if he hadn't reacted to the truck at all, there might have been no accident. As soon as he saw it and reacted to it (which was quite a ways off), he started pushing himself closer to its path.
This definitely wasn't an unavoidable accident. He could have trivially drifted back into his lane and all would be fine.
And there is no doubt in my mind that this is a demonstration of incorrect steering technique. That's what all that wobbling was about it (which again, started with the truck pretty far away), and the video later shows it clearly in slow motion.
Instincts will get you most of the way there, but you have to understand what's going on and practice it consciously in order to push your ability to take tighter, faster turns and to react properly in a dangerous situations.