Lars Brownworth's lectures on the rulers of the Byzantine empire is excellent. You can listen to them online here.

Mr. Brownworth teaches History at The Stony Brook School on Long Island, New York. His passion for Byzantine history has taken him on travels from the furthest reaches of the Byzantine Empire right into Constantinople, (present day Istanbul) the very heart of Byzantium. He has traveled and studied Byzantine history extensively and produced this lecture series giving us this concise overview.