This 40 minute screencast covers unit testing, mocking, dependency injection, and inversion of control.
The idea is again that this will be is very much a hands-on, practical screencast. Not technology for its own sake, but reviewing how and why these concepts evolved, and how they can be used in practice.
I'm not a TDD (Test Driven Development) fanatic, I don't think we should always have 100% code coverage with our tests, but I do think there is a lot of value in testing, and in making our code testable.
The screencast is available here http://damianblog.com/TestingMockingAndDependencyInjection.wmv