1) Drafting at IM races IS a problem.
Sometimes a major problem.

2) That video has nothing to do with IM drafting.

3) AKcrafty- "No matter what size the group going by...if I can sit at draft-legal distance behind the group and stay in my planned power zones, then I'm hopping on."

You probably realize this.....

But- there are often several groups, all "draft-legal distance behind each other."
All together.

Each groups of "legal drafters" coincidentally happen to be close to other groups.

This is often how massive draft packs form!!

Everyone is "legal distance" behind someone.

It's just a coincidence that there happen to be a lot of other people around.

True...
It might be that only people who are going rapidly backwards in the field see this.
Punishment for off the front swimmer's/ bad pacers