Idiots, it's the theory of how to rate someone and what to keep in mind when you do, instead of just basing it off the scoreboard.
How to do ratings: keeping the things mentioned in the video in mind, which I guarantee people don't generally do.
Whilst you might not agree Fred is accurate in rating Pyhon you can't deny that this is the way to think when rating a player. Hence it's how to do ratings.