It’s a really sad tale. It shows how destructive an indoctrination could be. I’m not saying that I am immune to indoctrination. Indeed, in some ways I think all of us are “indoctrinated” into a set of beliefs and frameworks of making sense of the world around us. It just happens that their framework is utterly distorted — although they would point back that indeed it would be us who are in rebellion against their god.
It is also interesting to see how the families try to be as thoroughly consistent as they could to adhere to their matrix of beliefs (e.g., in responding to some family members who left). You can sense that they themselves feel something is not right, but in the end they will rationalize it using their system of beliefs. And this is an example where coherence, as desirable as it is in the discourses of religions, may not equal to truth.
(You can watch the rest of the documentary in Youtube.)