Videotaping Protests?

Recently I was at a protest/waterboarding demonstration, and part of the protest was against military recruiters in plazas/middle schools, and so the event took place (originally infront of, but because they closed...) near a military recruitment centre.

Early in the day, a person in a white truck was following the protest and videotaping. As well as throughout the day random people who didn't talk/respond to us photographed us, but they were housewives so I think they were just curious or whatever.

What is the purpose of this surveillance?

I thought of two; either (A) they do monitor us and see how radical we get, try and screw us over indirectly with "losing" tax forms or something, etc. or (B) they're just trying to scare us.

I know that a while ago on ATS there was a topic with pictures regarding foreign agents videotaping protests in San Francisco, and "they" asked ATS for that to be removed. So what do you guys think or know?

hmm i could be wrong but i always thought it was illegal to take someones photo or video tape them without their permission, i know there are CCTV's around every where but they record the events in a specific location and seems to be a 2nd set of rules for them (id need to reserch that more) when you see them photograph and video tape them back and see how they like it

even better if you do post them here and see what kind of response ensures... if its allowed by the owner/mods etc