The 4th Faith Seminar in the 2008 Chicago Faith Series was focused on the role of the Saints in the Orthodox Church. In this video you hear Abey George, who is studying at St Tikhons Orthodox Theological Seminary, discusses important concepts as well as common misunderstandings.
Is There An Invisible Church?, by Protopresbyter Michael Pomazansky. This is much more an article on the Orthodox teaching concerning the Invisible Church and the Communion of Saints than a defense of the Visible Church.