If you've never had the privilege of hearing Kent Masterson Brown speak, you've missed a treat. I've had that privilege on two occasions (once at a Stephen Dill Lee Institute and once at Liberty University's annual Civil War seminar), and have always found Mr. Brown most informative and entertaining. I recently found a recording of the same talk I heard Brown give a couple of years ago. You can listen to that talk about General Lee and his retreat from Gettysburg here. This presentation was recorded at Lee Chapel in October of 2008.
It's well worth your time.