The video is called “Rediscovering Rachmaninoff — The Lost Liturgy of St. John Chrysostom.” It was on PBS in 1992, hasn’t been digitalized for online access as far as I can tell, but seems to be available for purchase here:
http://store.earthstation1.com/rediscovering-rachmaninoff-liturgy-of-st-john-chrysostom-dvd.html
Thank you for doing that research for me. I really do appreciate it.