Under the hood it installs remotion.dev, analyzes your styling to determine branding, and includes guidance for generating videos in hook/problem/solution format.
It also instructs the agent to create props for your scenes so you can tweak them live in the Remotion timeline.
PS: You don't need to install it - a skill is just a prompt. To test it, check the prompt here: https://github.com/alentodorov/create-promo-video/blob/main/...