Modern documentaries, especially American ones tend to repeat everything in case the viewer doesn't have anything more than a 2 minute attention span and to dumb everything down in case the viewer is of low intellect. I just watched an FBI bank robbery reconstruction documentary (well half of it - I was so pissed off at having everything repeated that I switched it off).
Why do they do this? Is it catering to the lowest common denominator ? A catch-all for the greatest number of viewers? If so then it doesn't work. I'm sure that the most likely viewer of documentaries is not the Rambo or Bruce Willis movie watcher.