If A Tree Falls: A Story Of The Earth Liberation Front (2011) ***

Excellent documentary. Sympathetic towards its subjects - the eco-terrorists - but remarkably objective and open-minded. And while it spends way too much time on pointless side issues ("it's unfair that eco-terrorists are treated just like Islamic terrorists, because they didn't kill anyone"), it's a fascinating expose on the process of gradual radicalization. And its insights apply to all kinds of political movements, not just environmental ones.