He never said God couldn't tell him anything, in fact, the man in the video said that he couldn't tell God anything about himself that God didn't already know. (If God really is omniscient.)
Yes that's what he said. Which presumes that because he "knows" that he himself doesn't believe in things for convenience, therefore it is a "fact" about himself, and that any God would also "know" the exact same thing.
It's as if the possibility simply hasn't occurred to him that it could be otherwise. He can't conceive that he could genuinely think that his beliefs are objective, and not based on wishful thinking, and yet he be wrong about that. It's as if he's never considered that his views may be based on wishful thinking on a level which he has not appreciated or perhaps is not able to appreciate. It's as if he thinks that God, even if he exists, couldn't possibly have a greater insight into his mind than he has about his own mind.
What if he were to say to God:
I never believed in you, but you know me God, I arrived at my beliefs honestly and never believed anything just because it was easy, but because that's the conclusion I honestly came to. You can't fault me for that God.
And God replied:
Well actually those beliefs performed this or that function in your overall worldview and enabled you to do this and that while believing yourself to be consistent. You may have believed you were acting objectively but you were fooling yourself in this way and for the following reasons.
Or indeed if God gave some other reply which contradicted his understanding of himself in some important way which we can't even imagine or begin to sketch out. Maybe not, but if it's almighty God we are talking about here, can we really rule out the possibility of a surprising or informative reply?
In reality there is a mountain of evidence that humans are extremely poor judges of their own motivation and limitations of their own knowledge. There is a deep irony involved in the fact that it is often those who claim to be the most ardent rationalists who are most reluctant to accept the clear and voluminous evidence for the frailty and limitations of the human mind.