Starting is super easy since he has already made a Docker container that contains all the necessary software. Docker is a new technology that allows you to package software environments to a single package (Docker calls these 'containers'). With it, the platform has a smaller impact, since the containers are platform-agnostic.
Normally this installation would take several hours since you need to compile Ffmpeg library for this. But thanks to Docker this compiled package can be included in the container.
The tutorial is referencing the Raspberry Pi Zero model, but the instructions will work with every Raspberry Pi model.