Ah, this is a video I wanted to talk about!
It's... ungodly long (and Sleepezi does make it difficult to follow with his monotone voice), so I'm going to make some bullets points. Some stuff was really interesting, other was completely wrong, some garnered a "eh". My biggest gripe with him is that he completely dismisses Tifa as a heroine, her role in Cloud's life, and that makes him misinterpret or forget some things. Seriously. It's just weird when the rest is so well-thought, that he has this giant hole in his theory.
So my biggest gripe about this video, it's that instead of having Cloud, Tifa and Aerith as the three main heros, it sidelines Tifa entirely and replaces her with Zack. And... for a theory based on *memories*, yeah... no. He literally skipped the very obvious fact that while Aerith is in charge of the external conflict, it's Tifa who is in charge of the internal conflict. There are moments of sheer brillance though, and things I also came to think before that.
On the wrong things, Geostigma does not transmit to those who have lost the will to live, what the hell. Cloud is a (lol) living proof of this since he was searching for a cure for Denzel when he contracted it, in no way did he want to die. Also he makes it sound like Cloud was settling for Tifa, which rubbed me the wrong way - he tried to move on with his life, with home bumps along the way in CoT, yes, but the thing is that he was happy. Tifa was not a second choice he settled for. She's always been his primary choice. He had a huge survivor guilt though, just like everyone in the party, even more so because he considers it as his personal fault that Aerith died. So he fears losing that happiness, and the happier he becomes, the more anxious he becomes about it, because he feels like a failure. So the whole part about this is iffy at best.
His going on about memories and how Aerith follows Sephiroth suit to "attach herself" to Cloud also feels like he's looked too deep at the quote that Cloud has her engraved in his heart and that he can see Aerith and Zack because they live inside of him. I don't think it's *that deep*, especially because it's probably a very Japanese way to think that people still live inside of you as long as you remember them (small ToTP spoiler: Jessie implies the same thing to Tifa about her father and Nibelheim).
I am not sure what he has read about ToTP, because he claims he used it for his theorycrafting, but I didn't see any trace (lol) of it in his video. Otherwise, Tifa would have a more prominent role. He's also using a CC Ulti quote about the Nibelheim incident saying that it changed completely the lives of those two boys and that girl (or something alike) and linked it to Zack, Cloud and Aerith while I think the girl is definitely Tifa - she's the one who has her life in shambles because of that event.
One of the most interesting theories is that Jenova has completely distorted the Planet's will by invading and corrupting the Lifestream. It would be especially visible in the Harbinger fight, where the huge Harbinger seems to have some graphic similarities with Jenova herself. While he may have a point with the Harbinger itself... I don't think Jenova has completely taken off the Lifestream as he said. It's definitely a possibility that what we're fighting off is linked to Jenova - it made me rethink about that part where Tifa gets attacked... it then would be understandable why *she* is the one who gets attacked, and not Aerith there - but CoLW versus CoLB and every material we've had up until now, Remake included, does not seem to agree with his theory (that would involve the OG story to be Jenova's will and thus be a wrong outcome).
Another interesting theory would be that Sephiroth is a prisoner of Jenova. In the OG, when Sephiroth lost his sanity, he had similar white flashes as we see otherwise when Jenova controls Cloud's mind. This would indicate that just like the others copies and Cloud, he too is called by the Reunion - which is showed in Remake as well - and he too is being controlled. Honestly... this feel like a touché for me. Then in Remake, Sephiroth's goal is to free himself from Jenova, which the party helps while fighting the Harbinger. It would also explains this ore/watashi use switch. To me, this is the most brilliant point of the whole video.
Now, I do agree that one of the major themes of Remake is "Memories" (well duh it was also a theme in the OG I guess with Cloud needing a specific memory to prove who he was), but I am not sure I agree about everything that's in there. Also to note, I have taken so long to watch this video that I might not remember everything. But forgetting the most important character (to Cloud) when it comes to "memories" will always leave me doubtful.