There's a good book for those who can read in french called Les Black Blocs, by Francis Dupuis-Déri, a political scientist at the University of quebec in Montreal (UQAM). The title underlines the plurality of the occurence of people donning masks and keeping proximity to each other, known as *a* black bloc. This has happened from Europe to the americas over the last 20 or so years. More info could be found quickly on wikipedia, a short little primer. There is no group that is The black bloc.
Who knows where the next moment that people will feel the need to protect their identities from the forces of order; but I was certainly surprised to hear the repetition of mainstream media propaganda in this otherwise interesting reporting.
Francis Dupuis-Déri researched the occurrence of the bloc(a name for a black bloc, not the one and only), and the goals and tactics used. Also extensively the proclamations of journalists, government, and police representatives over the years.
It can not be said that the black bloc is a grouping of apolitical hotheads, the communiques released regularly prove otherwise; it is a choice made by the logic of politically minded people. It can not be said that the block is always involved in aggressive confrontation, in the total history of the tactic. Much is said without any research. I'm probably guilty often myself.

Otherwise interesting subject matter in the video. Sorry to change the topic.