This is the only movie I have every watched that I have ever wanted to scream at. The (actors? murderers?) enjoy reenacting and reminiscing so much it's sickening. One of the most powerful moments was when the man responsible for leading the paramilitary organization responsible said that killing people with piano wire was the most "humane" way to exterminate the communists and that they didn't want to look like bloodthirsty animals on the film (or something to this extent). I love absurd movies, especially violent or shocking ones. But when you know it's all real - the murders, the torture, the smiles as they reenact it all - it's completely different.
[spolier]Anwar looks like he finally starts to realize at the end what he did was wrong, but he won't even say for sure. He seems so conflicted.[/spolier]
At any rate, it's a slow burn but very much worth a watch. If you ever need a movie that's the perfect definition for the "banality of evil" this is it. Hang around, make a movie, smoke a cigar, casually talk about how much you enjoy raping 14 year old girls and genocide **on camera**. There are more of these moments, too many to list. Watch this film.

The synopsis is available elsewhere and I have no idea how to review a film like this so here are a few simple lines: I have never seen anything remotely like this and would go as far as to say that it is one of the most honest portrayals of several aspects of the human psyche I have ever experienced in any medium. It's not a pleasant film but I can't give it any less than full marks for its bravery, arrogance and honesty when dealing with an uncomfortable aspect of our species.

Joshua Oppenheimer (dir.) understands the social norms of his subjects' environment and also their own egos and greed, shows us so that we also understand and then uses all he has learned to get them to openly reveal all directly to the audience, pretty much by luring them. It's obvious that with the backstory and footage used he already had more than enough for a documentary film and it seems as though he thought 'I have a better plan' and then made this film instead, in the ultimate quest for knowledge. Beyond words and essential.

Note: There is a companion to this called 'The Look of Silence', which is a different type of film altogether and one that sheds much extra light onto the the events of this time and place but from a different perspective and this is also recommended, albeit not as strongly.