This tutorial is by Frank Rueter. Visit his website for more : http://www.ohufx.com/
This shows how to use the Precomp node in a workflow that enables the artist to use external NUKE scripts as an input to their main comps. This helps to keep the node graph tidy, but also opens up the option to work with centralised NUKE scripts as inputs without having to pre-rendering them.
Such a workflow is invaluable for shows that need to share the same NUKE script as a background. For example, only one NUKE script needs to be changed to update all main comps that depend on it across multiple shots.
This tutorial shows you how to set up such a script dependency and how to work between the precomp and the "receiving" comp.