Clear Channel may sell a lot advertising space, but not advertisements. Clear Channel is a primarily radio/billboard company, owning thousands of radio stations and billboards. They also own TV stations but are in the process of selling the division off...

which uses compression to improve online videos.

so they are divX clips then?

Also benefactor of the University of Texas Red McCombs School of Business and attempted purchaser of an NHL team (can't remember which one, a Canadian one, IIRC).

Someone once called Clear Channel the Microsoft of radio, but they're more like the Walmart. And all the Democrats in Congress point at them as a reason for more regulation of the airwaves.