ABCNews -- If you've ever seen Comedy Central's "Daily Show," you've seen 21st century free speech in action. A few seconds of an ad here, a few seconds of a newscast there, combined with Jon Stewart's comedic commentary -- and voila! A modern-day mash-up that samples digital bits and pieces to create something new. But where does one person's creation end another person's begin? Though copyright holders certainly have the right to protect what belongs to them, in some cases, the so-called fair use doctrine allows the limited use of copyrighted material. To be sure, fair use legalese is complicated stuff. But digital rights advocates, like the Electronic Frontier Foundation, argue the importance of defending the use of copyrighted video, music and...