Here is the paper titled "Skier Responsibility Code" (sic):
It should be easy to find references to "common sense", "best judgment", "courtesy", and "awareness".
Couldn't disagree more. Of course a skier needs to watch out for anything that may cause him/her injury or damage.
The bottom line should be -- while skiing, do all you can to avoid injury, equipment damage, etc. to you or people around you. That includes avoiding skiing along the tree line in collision zones, like the tree line in the video, where tree trails merge into the piste. This topic wouldn't exist if AngryBully was aware enough to move 10 ft or more to the right, regardless of TreeDude's violation of the rules. That would give all participants in this crash enough time and space to react properly.
Again, I am not making excuses for TreeDude, as has been implied to me on several occasions.
Also, the resort should put a "Trails Merge" signs in the area, it would help avoid collisions like this.