Yeah I didn't read through it earlier. Seems like there are 3 parts from my understanding. You need some motion capture service like Rokoko/DeepMotion to create BVH files describing the movement from a video. The algorithm this guy created animates/renders by taking the BVH and an annotation file from the drawing. But the project did "train a drawn humanoid figure detector and pose estimator and provided scripts to automatically generate annotation files from the model predictions" so that part does have machine learning.

I would love to use this for my old animation website https://www.superanimo.com/ But due to the AI boom I have tons of work to do on my other projects, so I can't sink time into modernizing my crappy animation site.