Swami Sarvapriyananda: Mandukya Upanishad, 1 of 6 thru 6 of 6. It's about 6 hours on the shortest Upanishad and a great insight into Advaita Vedanta non-dualism.

https://youtu.be/scLipiyG6ns
https://youtu.be/Onm_8r7TiVE
https://youtu.be/MLuUl-mjk4k
https://youtu.be/5ieoVJ4dDSw
https://youtu.be/SSeT9Ewofu4
https://youtu.be/C9dIve89q9Q