Video interviews give us the opportunity to discern the sincerity of the speaker. Watch their eyes & facial expressions. With a couple of the speakers I got this distinct impression that they didn't really believe what they were saying was true.
One scene that really doesn't ring true. Is after being told by one GB member that Rutherford was brusque in manner and didn't fear to tread on anyones toes. We then see a reenactment of him stoically standing by and not defending himself while he is being harassed by his opposers
Overall though I think it is a fairly well done piece of propaganda