It is hard to understand how a population can get so incensed over a video, a cartoon or an ignorant statement about the Koran. One has to live in a closed, homogenous society to fully grasp how something like this can happen.
Sitting here in the U.S., we can pass judgment on people and their lack of tolerance, and there is merit in that. But poverty, lack of education, lack of debate and pent-up anger and frustration over life's stresses make up the root cause of such violence. Additionally, the governments of these countries are useless in preventing the riots.
There is no excuse for such a virulent video mocking Islam, but there also is no excuse for this violence.
As a headstrong nonreligious young woman in the 1960s, I lived in the most orthodox area in Jewish Jerusalem. One day, I went up to the roof to sunbathe in my bikini. Before I knew it there were eyes everywhere and the neighborhood was in an uproar.