It prompts "gigantic alien tentacles that destroy the world."

I suspect you're reading the base prompt, but the video also demonstrates adding further prompts to change what is happening as the scene progresses.

It was the complete lack of fear or urgency on the part of the characters for me.

But remember, today is the worst the models will ever be. I agree they are still safe though... they will probably use AI to make even more films faster and more creative since it enables them to do more.