Rene Fielding rushed to the area so she "knew" there was no danger? Ok, that is pure guess work but go for it.

She ran to an officer and asked for something. Gloves, as a trained professional she knew where to get gloves, probably because the officer is already wearing a pair.

The policeman is not the same person as can been seen by the different colouring in the jacket.

So the Acting Director of Emergency Management happens to be at the biggest event in Boston's calender and it is because it is her job to be there. Not to stage mock terror exercises but to be there in case of a serious incident.

The yellow shirt guy is a competitor, you can see his number on his top. He has run 40km and yet he helps other people, what a bastard, he must be an agent.

It starts to get into some really deluded shit right about now involving stanching and cosmetic dressing...you want to know something, probably not but I'm going to tell you anyway. When someone is badly injured the sight of their wounds can make some people really freak out and start becoming hysterical. Covering them up can aid the patient in remaining calm.

Rene Fielding is smiling because it is art of her job to create disaster? How about she is smiling trying to reassure someone who is in the middle of the most traumatic experience of their lives.

The only evil manipulation I see here is the maker of the vid who is deliberately misrepresenting everything and then using extremely negative and emotive language to try and convince you that there is more going on than meets the eye.