Did you make the video? It look's somewhat similar to 3Blue1Brown. Are you using the same package to animate it?

Is this about light/dark fonts or light/dark colors? (Is the title here wrong?)

How did you get the training data. The classification of light/dark colors is somewhat arbitrary.

Do you have an example where this method to classify colors is better than the linear r*p+g*q+b*r>.5 ?

A simple neural network predicting a light or dark font, and animating the forward propagation