I can speak and understand Thai well, but this documentary is not going to keep attention, because although it has multiple levels of credibility, the right people, the right questions, and the right topic, if you're not used to going to a Thai-style lunch table conversation with notable and knowledgeable people, it's simply not presented or edited as what we're used to with our Ken Burns and Morgan Spurlocks.
Also, the format is unique, not that I prefer it. They do not do a good job of presenting background information using a skilled narrator and beforehand, you sort of discover the circumstances and have to speculate/extrapolate to form your own mental image of a situation that's not too well documented in the first place (although this can account for the lack of stills used in this), and the author simply defers to the use of overlaying interviewee voice with just video of setting, surroundings, or observers who happen to be at the interviews/conferences.
It also relies mainly on video footage that follows the interviewer/filmmaker. There's little to no transitioning between story elements.
I still guess you can call this a documentary, but it's more in the sense of a documentary photographer (a photojournalist) except one who does not work with a skilled editor or writer.
It's good for what it is, simply because there is not much better available. Except it can be presented in such a more coherent fashion by defaulting to some of the tried-and-true narrative and documentarian techniques that is prevalent in modern documentaries. It has no reason why it needs to be close to four hours though.