I think the lack of uniform is just the first visible clue. It's not the first time, certainly the concept of guerrila warriors hiding in villages is not new...
These guys have just taken it a step further. They learned about us from our outrage over burned innocents in Vietnamese villages and they will use our own ethics against us. Those villages also had non-uniformed combatants in them. And those stories played on our news and in our movies and horrified us. Those images shake our confidence because we are moral. It's our morality that makes us rip and tear (and roll the live camera) at each other for mere mistakes in judgment in war.
They riot over the suggestion that a book was ruined... not because they give a damn about it, I don't think, but because they know that their riot will make us fall all over ourselves with guilt that we might have offended their sensibilities.
These guys know us. They know our news, and we don't know them well enough to know they are using us against ourselves.