I don't think i ever mentioned anchor man. I said Donnie Darko. I don't remember him much in anchorman, but i'll take your word for it. Also, he was a main character in Freaks and Geeks and everybody on that show was unknown. It was a show with most all unknown (at the time) actors. In donnie darko, he wasn't famous and probably just took any job he could for money. That's what i think when i think "extra". Cameos are usually already semi-famous people making an appearance in a movie either because the movie makers wanted to say that actor was in the movie, because it'd be "funny" to have that guy just appear for a second, or the actor knew the director/other actors and just wanted to be a part of it for a second. Extras are normally non-famous people in the sea of millions of actors just trying to take whatever job to make some cash. Sarah Silverman was on an episode of Seinfeld now that i think of it.