Seek screencast demonstrating the act of inspecting a code expression tree

Text is great for lots of stuff but not for a 'start-from-scratch' understanding of 3.5's Linq.Expressions (- at least not from the POV of how the GUI can be employed to explore a code expression tree) I have access MSDN (i'm sure they would have some well produced content - am interested in alternatives too) but would like help navigating to the the best intro/overview of this specific subject.

thx

UPDATE: This is one of those 开发者_开发百科times where the pictures are worth more than words.