I have listened to a great and short lecture about the mystery of the Eucharist for Dr. Joseph Maurice Faltis and I had to share it. He speaks about the mystery in a very simple way to the point that I don't think you can consider it 'a lecture' but he truly provides us the clear faith we, as orthodox, have:

He is speaking in arabic, in the simplest form, and there is english subtitles for those who need.