alex - i htink you'll find that the evidence gathering team were there at the request of the club as was the increased police presence.
the only time i have seen evidence gathering teams at our stadium is at the away end. someone somewhere asked them to film our end today. i strongly suspect that this would have been our 'match commander' or his boss...
as scotty said, there have always been cctv cameras about the ground - this was different and i suspect came from mr smith being unable to identify supporters in the north stand at the game against cellic in october. what the fans did on saturday was not against the law imvho but would be getting up the club's nose and they don't want anything to happen that may rock the boat.