This tool grades against doctoral-tier standards. Most YouTube content lands in the F or D range — that's not a flaw in the tool, that's the gap between media training and scholarly rigor.
A low score is the opening move in a dance, not a verdict. The ego takes a blow so the essence has room to step forward. Roll with the punch. Refine. Grade again.
Read the elevation-coaching block at the bottom of every report — that is the part of the practice you take with you.