ambassador -- >> when celebrities come to washington, the media and the politicians take notice. but does the spectacle of the star outshine or shed light on the cause they've come to promote? >> often hearings in congress are not about members of congress learning something that they don't already know. it's performance art. if they want to learn about issues they can get it from a book. >> today oscar winner ben affleck arrived in washington to speak about the crisis in the congo. >> pleasure to be at the real state department. i had to fake it for "argo." i get to see the real thing here. >> the "argo" director has brought his cause to the table time and time again. >> my name is ben affleck. i'm working with and for the people of eastern congo. >> and today just a few marble pilars away actor seth rogan testified about the effects of alzheimer's, which his mother-in-law suffers from. sure, these appearances bring some buzz.