Would it be difficult for Canon to make a firmware update that would allow you to see the histogram BEFORE you shoot video? Or even better, when the 5D MKIII comes out, maybe have a dedicated H button that you press to toggle between the scene on the LCD and a histogram of that scene. Wouldn't that be a quick and easy way to eliminate uncertainties about the proper exposure? If the histogram is too far left, add a stop of light. Too far right, stop down.