I had the same thing happen (Firefox under XP).
Latest quicktime, apple site, no video displayed, just the 'get quicktime' link.

I'm not sure what the problem was.
But, I hit a different quality link and it began to work properly (play video). It worked for all three ads, even after I went back to the original quality setting.

I think the plug-in just wasn't initializing properly. The 'get quicktime' link displays while it's loading as well. It's possible that it's trying to phone-home and was just timing out or going particularly slow due the traffic.