As I understand, this started out as a protest against underfunding and other problems in the schools in (formerly East) Berlin, but was used by some people for nastier purposes. The protesters included schoolchildren - (who perhaps demonstrated by some of their behaviour that their schools were indeed not educating them adequately! - and members of the far-left 'Black Bloc'. The latter is a rather disorganized bunch of anti-globalization, direct-action proponents, of whom a certain section are prepared to support violence. Here is an article about them from a year or so ago:
http://www.dw-world.de/dw/article/0,2144,2578933,00.htmlThey appear to be a significant - and sometimes, as here, scary - problem in Germany, but should not be seen as representing the mainstream left. The article was somewhat misleading by calling them simply 'left-wingers'.
Destroying an anti-Nazi exhibition is antisemitic, not simply anti-Israel; and may represent a rebellion against the German establishment and its commitment to 'denazification' since the end of the last war.
There have always been some commonalities everywhere between the more violent elements of the (so-called) far left, and the more anti-establishment elements of the far right. It's not a new phenomenon, though the internet may make it easier on the one hand to spread these attitudes and on the other hand - hopefully - to fight them.