Only thing I can think of is that your internet or router or something is blocking you from viewing it. It's working fine for me, I tried it a few times and it worked every time. I have it working in Firefox, Chrome, and Internet Explorer. I haven't had a chance to install Safari yet, but I'm sure it will work fine too.
Just an idea...
Go to YouTube.com and then try to view a video. It will ask you to install Adobe Flash. Click the link it gives you. Follow the directions exactly as they have them. See what happens. I really don't know why it would do this though.