[font=verdana]It’s important to be clear whether you’re talking about reproduction quality (ie, what resolution is it filmed in, is it a good, steady picture with a high bit-rate … or is it jerky, pixellated and fuzzy) and content quality (ie, is it entertaining, informative, well-directed etc). You seem to be implying that Google ranks videos based on their reproduction quality, which I find unbelievable … that would require them to manually assess each and every video, which just doesn’t happen. If they can’t automate it, they don’t do it. I can find no evidence that Google gives higher rankings to videos in HD than normal.
What you may find is that HD videos are more popular with viewers, meaning that they share them more quickly and more widely … and it’s true, that will improve your chances of a good ranking in Google, but don’t get the cause and effect muddled up there … if your video is boring, it doesn’t matter what resolution it is shot in![/font]