the tl;dr version is that they created a relative ranking system. They did give arts a letter grading, with S at the top, then A through F, though I think in the end it was calibrated mostly to be a ranking of arts relative to each other.
The simple criteria was how well prepared folks were after a 'year or two' of training in the styles as they are commonly trained.
The video is so long, because they actually chat about each style at length, so whether or not you agree with them, you'll at least understand their rationale for where they placed the style and why.
So, the question is, how would you rank the following styles? If you don't know or aren't comfortable ranking a style, just ignore it. If you're not interested in participating, it's okay. Don't sweat it. Just a little fun. I'll list all the styles out below, in the order they ended them with in the video.
Tier 1: Wrestling and catch wrestling
Tier 2: GJJ and MMA
Tier 3: BJJ, Judo, Muay Thai, and Lethwei
Tier 4: Kickboxing
Tier 5: Western Boxing
Tier 6: Capoeira, JJJ, Karate, JKD, Kenpo, Krav Maga
Tier 7: Kali/Escrima
Tier 8: Aikido, TKD, WC
Tier 9: Ninjutsu, Pencak Silat, Systema, and Tai Chi