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This does'nt appear to be a heat of the moment thing, it seems (for a demo) quite quiet,they are trained to deal with these instances, so no I disagree with you Elvis.
I am more than happy to cut the police a bit of slack (such as the De Menezes case) but this does'nt qualify to my mind, he's not bothering them, he's not looking at them, his hands are in his pockets, he's not shouting at them and he's walking away.
Why did'nt they just arrest him after snatching him from the street?
Noone's answered that yet.