It was 3 minutes. You can't sit through 3 minutes of video?
Here, I'll lay it all out in text for you instead...
-how could God be certain of his own omniscience?
(excluding responses like "it's possible for God to know he's omniscient because he is omniscient")
-a. if God is truly omniscient...
then God would think that he is omniscient
-b. if God is mistaken in his omniscience...
then God would still think that he is omniscient
Both scenarios lead to the same conclusion, therefore it is impossible for God to know with absolute certainty which premise he is working from, a or b.
To put it more formally;
1. If God exists, he knows the truth-value of all propositions with certainty
2. To know all propositions with absolute certainty, God must know with absolutey certainty that proposition "God is not mistaken" is true
3. If God is mistaken, he would not know that he is mistaken
Conclusion;
God cannot know the truth-value of the proposition "God is not mistaken" with absolute certainty
and so, if you take this farther and if you apply the omniscience character trait to your God, then God cannot exist.
I'll be awaiting your reply.