Lightening the video will only help if the information is there to start with. For a simple test, capture one frame of the video and import it into Photoshop (or whatever), then use the brightness/contrast control with preview to see if you can bring out any more detail. If you can't then it is unlikely that you will have any joy with the video.
What it boils down to is the "colour-depth" of the dark areas of the picture. If what looks like black on the screen is encoded with 20 different shades of darkness, then you might be able to bring out some detaill, but if it's only one or two then you're out of luck.