http://www.bbc.co.uk/news/world-europe-24902058
what. a. total. bullshit.
I've seen few different coverages, compared them together. and i can reach only one conclusion of that: total bullshit.
the march had to organize its own protection because it couldn't trust the police(last one, and the one two years ago were obliterated by provocation by either police or anarchist groups - http://www.youtube.com/watch?v=1r6dotpqGf0 example of undercover policeman attacking a passer-by, later confirmed to be 100% innocent, guess what the consequences were for the policemen... none).
Whole march was peaceful, ppl waving flags and all, singing patriotic songs and occasional flares/fireworks - the rainbow arch 's mini-park wasn't even a part of the march's route -and it was always burned/destroyed down when it was repaired, so blaming this on the march is kinda retarded. the march also got attacked from squatters building - someone was throwing rocks and bottles on them. Embassy incident was retarded, but well - it was small group of ppl, 10-15 ppl maximum from what i've seen.
Also - the Warsaw's city hall decided to delegalize the march when it was very close to the end, with police blocking the other routes than forward - therefore giving the police legal reason to attack it, and no real way for the march to comply to the delegalization.
even if you count the misbehaving ppl, the ones that 'attacked' the embassy, and provocators you'll totall them at 200-300 people tops.... march had 50 thousand people in it.
oh, did i mention that police could prevent the embassy incident by putting just few guys in front of it? yep they didn't even cover/protect the march's route. they waited for people to do some retarded stuff(probably some idiot anarchists) and they did nothing to prevent that.
about guys wearing masks - well, it is legal.