Why i cannot view videos in youtube?

Hello,

I just upgraded to internet explorer 8 and try to open you tube to view some videos. It won't play and the message like this will appear "Hello, you either have JavaScript turned off or an old version of Adobe's Flash Player. Get the latest Flash player."

After reading it, I immediately downloaded the flash player 10 but still it won't play. I enabled my javascript on the internet options-security-custom level-enable active scripting. but still it doesn't work and play yet.

So what's wrong with this? how can I fixed it? I attempted to downgrade to internet explorer 7 but the message was it won't support my operating system. PLEASE HELP ME.. I'M REALLY WORRIED WITH THIS..