Thanks Admin,
Once again, you're on top of your game. I just tried uploading the video to Bizhat (http://video.bizhat.com/view/1326/snow-angels-trailer/), and there again was no thumb generated. So I guess it's a problem with the video and not with my site. That's still strange though...both videos were from Yahoo Movies, so maybe there's something in their encoding that screws with the thumb generation.