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 wanted to really learn about issues, they could get it from a briefing book. reporter: today oscar winner ben affleck arrived in washington to speak about the crisis in the congo. just a pleasure to be back here in the real state department. i had to fake it for argo. reporter: the argo director has brought his cause to the table time and time again. my name is ben affleck. fought on congolese soil. i m working with and for the people of eastern congo. reporter: and a few marble pill ars away the actor seth rogen testified about the effects of alzheimer s which his mother-in-law suffers from. sure, these appearances bring some buzz, but ultimately does anyone remember why stephen