It is very difficult. I have been to a RC fly in where we have dog fights. 30 of them in the air with experienced pilots trying to cut each other down and we rarely have a collision, sounds like a bees nest for a while until everyone runs out of fuel or battery. One would think it would be easier, but it is not, fun to try though.
As for video recording anyone in particular, if they happen to be in the video then fine, but it's kind of like a person who runs a dash cam on their car which is becoming very popular for personal protection during a court case, if they are driving cross country and someone happens to get in the picture, then someone happens to get in the picture, but that isn't the actual intent of the video. I don't hover mine over an area unless there is a reason, and unless a person is being attacked by a pack of wolves or something rare, I don't see a reason. I don't fly mine in populated area's either, simply because there is nothing there I want to see unless there is a flood and I"m looking for people on top of their roofs needing a ride, then you can give their location to the right people and they will come and rescue them.
I understand people not wanting someone abusing the equipment, but I also don't want to be on a cross country flight with a $7000 piece of rescue equipment and have someone shooting bullets at it because they don't like it in the airspace for a short time while en route that happens to be over their property.
