go watch all the footage and then tell me where they conveniently start
The video at the link you posted is 9 minutes long and starts after the initial confrontation.
You can go online and find any twist to this you care to.
If there is blame to be cast, I personal think it would land on the chaperons from the school that were there to look after the kids.
Right or wrong isn't the point, it's letting a minor get his face involved in in potential viral event when you were sent along to look after them. An event that for these kids may very well effect their enrollment at their school.
If thats worth it to these kids and their parents, fine, they did right in their view.
In all the accounts of these events that were taking place at the National Mall these kids involved them selves unchaperoned in the manner they felt was appropriate at the time with no one forcing them to do so.
I really don't care myself what the kids did or why, I do care that they were allowed to do so on a chaperoned trip without the support of their chaperons. Maybe if someone had been watching over them they may have stepped in and just said something like, "OK boys, thats enough".