Was this done with an LLM? Repo?
I thought the same way when I saw some impressive AI-generated videos not long ago, and I suspect the author prompted AI to get a basic idea, and then possibly after many iterations, finished it up with manual editing.
https://drive.google.com/drive/folders/1aIbRs2f6sVpCxO4TGoBf... (direction-log.md shows all the human provided input). It is far less than you'd think.