A score that flattered bad video
The first scoring model averaged the six scales. A recording with good exposure, good framing, reasonable pacing and almost inaudible speech scored well, because one catastrophic dimension was diluted by five acceptable ones. That is precisely backwards: a video nobody can hear is not a good video with one flaw, it is unusable.
Weighting the final score 60 per cent toward the weakest scale fixed it. The general point is that an aggregate is a choice about what you are willing to hide, and the default choice — the mean — hides exactly the thing you most need to know.