Here's some very informative videos from Dr. Monteith.
A FEW VIDEOS HAVE 30 SECONDS OF BLACK LEVEL BEFORE IT STARTS
http://video.google.com/videosearch?hl=en&q=Dr.+Monteith&oe=UTF-8# (http://video.google.com/videosearch?hl=en&q=Dr.+Monteith&oe=UTF-8#)