The video is convincing at face value but the snoke bit is off. People had the same complaints about Palpatine in RoTJ and for good reason until the prequels explained him.
I literally cannot remember anything about the time before the prequel trilogies since I didn't even watch the OT's until after the PT's, but my understanding is that people mostly didn't care. And just to be clear, even with the prequels...we still don't actually know anything about his character. Mostly what we learned was how stupid his plan was and how stupid the Jedi had to be to fall for it....
But what do we actually learn about Palpatine? What about his motives, what about his internal desires?
Nothing. He's just this power hungry, corruptive evil old dude that wants to be emperor.
What does he want power for? Nothing. He just wants it.
Does he have any internal character struggle? No, he doesn't have any regrets or insecurities or shame with his actions. He cares for nothing but power.
Do we learn anything about his past? Well, yes actually. We learn that he learned from some other evil old dude, that he then killed. Wow, what a revelation that a power hungry bastard would seek a mentor only to dispose of him once he got what he needed.
Did he change at all in the prequels that help better inform us of his present character? No.
The prequels aren't meaningful development. All you really learn is that the Emperor was exactly the kind of scumbag as slightly younger version of himself you would assume he was based on what kind of scumbag his slightly older version was.
All he is is just an evil old man who dicks over everyone in his quest for power and all you really learn is the specifics of how he dicked over the Jedi. That's it.