How many other "shes" did you see in the videos in question?

It's just not a serious argument.
If something can never happen because I would never want for it to happen, and I know for a fact that I would never change my mind, that makes me the most powerful being in the universe on that one thing. Expand that one thing to every thing, and I am all powerful.
If you are asleep and dreaming, and you have total control of your dream and cannot for some reason be impacted by anything outside of the dream (pretend you have a forcefield preventing all contact with the outside world), are you not simultaneously omniscient and omnipotent in the context of the dream? After all, nothing can happen without you thnking of it happening. Your knwoledge that you are the cause for all things does not make you any less powerful over them.
Your entire argument is based on the idea that god and the universe must be separate things. They are not - the dream is part of the sleeper.
If you know at the beginning of the dream exactly how the dream will play out, then the dream cannot play out in any other manner. If the dream cannot play out in any other manner, then you are incapable of controlling the dream.
No, the argument is not based on the idea that the universe must be separate from God. God's relationship to the universe is rather irrelevant. Even if the universe did not exist, if God knew infallibly what actions he would perform on his own, he'd be incapable of performing them any differently. Your objection that God knows he'd never change his mind misses the point. I have already showed why preference doesn't matter. The point is that if things can only happen one way, and God knows the way in which they will happen, then he is
incapable of doing anything else. If God is incapable of
anything he isn't omnipotent. It does not matter if God wants things to happen a certain way, and his actions make them happen that way, and he simply won't change his mind about the way he wants things to happen, it would be
impossible for him to be able to do anything else. You cannot know what will happen and be capable of anything else.