The Microsoft internal testers have put together a series of whiteboard sessions on testing the Windows development platform.  In this Whiteboard session we have Shozub Qureshi walking through testing WPF Controls.
To view the video please see the channel9 site:

http://channel9.msdn.com/posts/Charles_Sterling/Testing-Windows-Presentation-Foundation-Controls-WPF/

For more videos and information on testing in general please visit the Tester Center at: 
http://msdn.microsoft.com/testing