mohammed abbas took him aside and told him to put it away. >> reporter: abbas then explained to me what was going on. >> reporter: you want this man to go out of here? >> reporter: they may be playing down their role, but the real question is what are their long- term intentions? i went looking for some people who know the brotherhood. mohammed kamal is one of the more moderate leaders of mubarak's national democratic party. the party's headquarters were gutted by fire in the early days of the uprising. many in america fear islamist movements. are their fears grounded? or are they irrational? >> well, i think some members of the muslim brotherhood have fundamentalist view of the world, and of egypt for that matter. they will try to use the democratic mechanisms to come to power. and once in power, they're going to restructure the whole state to fit their ideology. and i don't think they will leave power afterward and egypt might become a second iran. but there are others, also, who- - especially from the young generation-- who wants to be part of a modern state, a modern civil state. so

. >> reporter: on tahrir square, i found mohammed abba, a leader of the muslim brotherhood's youth wing. for the past month he had been working alongside secular activists from the april 6 movement to help organize the revolt. he was eager to show us what he and his fellow brothers had contributed. it was not until three days into the protest that the muslim brotherhood senior leadership officially threw their weight behind the revolt. now the brothers were running the security check points. serving hot tea, distributing blankets, printing posters, and running an emergency health clinic. they call themselves the brothers. in arabic, they have decades of experience providing social services to egypt's poor. they became key to holding the revolution's infrastructure together. >> we are the best who organize. >> the organization is in the brotherhood's hands. >> reporter: this man is an expert on arab political movements. >> the garbage collection, tea cups and so on and so forth, even one microphone or the two microphones which we have to address the crowd they are owned by the muslim bro