Tuning a Half Step Down

This is a 2.65 minute video response from Mark Lincoln on Feb 3rd, 2009

Question:

"Wcanderson asked "This question is for Mark Lincoln. I am on lesson 4 of your beginner set, and I noticed that your Martin is tuned 1/2 down. Do you prefer to play this way? What are the benefits, and is the key change weird when you play with others? Thanks.""