https://www.youtube.com/themodernhermeticist
Many P. Hall discusses the Eleusinian Mysteries
Please note, this is an old and relatively 'out-dated' recording as much has changed in our understanding of what transpired at Eleusis. There are a number of good recent publications which one can turn to for more up-to-date information about the Athenian state mysteries.
Manly P. Hall was the embodiment of the interest in esoteric and 'theosophical' matters so prevalent throughout the Victorian era. Once the colonial powers of Europe had thoroughly spread out their dominions around the globe, European scholars voraciously collected and translated a wealth of esoteric literature from numerous ancient cultures. This was quickly gathered together and interpreted using a predominantly comparative method (today it is no longer very fashionable to do this: scholars try to view cultures on their own terms, with language they themselves used.) Today, however, Manly P. Hall's recordings and books have become timeless classics, as they are windows through which we can get an understanding of how late 19th and early 20th century occultists and antiquarians made sense of the ancients' myths and histories, and how they integrated such knowledge into their world.
For a copy of Manly P. Hall's Magnum Opus, the Secret Teaching of All Ages: http://amzn.to/1XXf1iB