ॐ पुर्नामादाहा पुर्नामिदम पूर्णत पुर्नामुदाच्याते ।
पूर्णस्य पुर्नामदय पुर्नामेवावाशिश्यते ।
ॐ शांतिः शांतिः शांतिः ।।
This is complete, and what comes out of this is complete.
Though this has come out, and though this is complete, that is also complete.
When completeness is removed from completeness, what remains is completeness.
When completeness is added to completeness, what comes out is also completeness.
He goes on to describe this by the creation of a pot of clay from clay. Note his breakdown of the word Upanishad and his explanation of how Upanishad is about illumination and not instruction.
In the second part, he says that the Upanishads directs us to be heard and listened to, and not to be read and studied. According to him, "listening has to be done with the ear and the mind plastered behind the ear." Total silence is recommended to listen something. Another interesting point that he notes is that all the shastras are in the form of a dialogue and not a monologue, started with the student asking the teacher a question and the teacher answering him, which is exactly opposite to the examination system prevalent today. Also note his division of humanity into categories depending upon a person's inclination towards learning, and defining who can be a student to the Upanishad.
Conclude the video series by viewing this clip as well.
For more on the Ishavasya upanishad, refer here: click