When I try to watch a WWDC Keynote from Apple's website, it opens up QuickTime, loads up and when the video starts I can hear the video but I can't see the video. It just shows QuickTime's logo and the bar that shows it's loading at the bottom. Is it because of my slow internet connection or because my PC is too slow? I have a PC with a Pentium D 3.20 GHz and two gigabytes of RAM.