+1 on the Todd Jarrett vid. It was recommended to me when I got serious about pistol shooting a year ago, and really changed my shooting. Pay particular attention to what he says about consistency and your grip "wrapping" all the way around the gun.
Also take a minute to read this article ---> http://www.handgunsmag.com/2010/09/2...ombatg_100306/
from G&A. I know you asked for videos, but there's pictures in this one and IMHO it really is worth the read- particularly the "straight thumbs" method.