This is my third screencast on Enterprise Library 4.0. The first two being:
The Logging Application Block with Unity Screencast walks you through a Model-View-Presenter Example that shows you how to register Logging Application Block Configuration Settings with Unity via EnterpriseLibraryCoreExtension and LoggingBlockExtension, register type mappings into Unity, and have Unity inject a LogWriter Class into a CustomerDataSource to be used for logging messages to the Rolling Flat File TraceListener.
You can download the screencast here:
You can also view other Patterns & Practices Screencasts.
Logging Application Block Tutorials