This video has only just surfaced and relates to events around Xmas before the mass protest.
And I agree the treatment was dreadful.

 If i have to do any street photography I will carry a copy of the rules and also wear my bright safety tabard . This way I cannot be accused of lurking around sneaking photos so that under anti terrorist laws the police would be a laughing stock if they arrested me. Also i would provide my address in the form of my business card because I never pass up a chance to network ! Certainly I have a choice about giving my name and address, however in my opinion I would rather avoid giving any PC an excuse to mess me about.

In Autumn last year I had an hour to spare in Inverness and pointed my camera all over in full view of the huge network of security cameras and also included police cars. traffic wardens etc with my zoom. I was never asked by any PC what i was doing, and two walked past me.

And remember,  when stood on private property you need permission to photograph people but when on public rights of way you can snap away.