CGI = computer generated graphics.

Human made CGI involves working with video editors, 3d model/texture/render, animation using math and physics (eg: coefficient of viscosity for fluid, friction, gravity, force etc), and many other awesome tools to do these things.

AI produced CGI involves 0 of those things. Let's say you want to produce an animation of water flowing through the tube. Traditional CGI is the human way, involves math & physics and a lot of computation.

Now imagine training a neural network with millions of moving images of fluid of various viscosity and making it able to guess every next frame, if you give a start (context) and current state of the fluid (particles), it would be able to predict every frame after that. It was trained on data we generated using math & physics, and now it doesn't need it.

Just like you when you learned how to ride a bicycle. Go figure.