It is a yahoo ad. Yahoo controls how they change and pays Corey for using the ads, and per click. I know, I use them too on other sites. Since Yahoo would not set people to just change the ads every time they want to, it automatically changes to the content. However, there might be a long period of time where the bar waits before refreshing. To change this, Corey would have to ask Yahoo to change that, if it's possible at all.
~~Ben