Oh okay, I follow where you were going now. No, I understood that there was just a mechanism (inversion) to allow you to travel backwards in time, but I can kind of see how you would get the impression you got - objects are existing backwards in time and maybe they belong to people who live backwards lives as well.
It's a convoluted plot, and I have to wonder why Nolan thought it was going to be an 'earth shattering' film for the masses. Like most Nolan Sci Fi films (The Prestige, Interstellar, Inception), it's a cerebral puzzle that's going to attract a niche audience. Usually the action in these films is enough to bring in other people who may not understand, or even care, about the science.
That same Youtuber has several videos on Tenet that are worth watching. I was reviewing them last night to get ready for my rewatch of the film. There's a whole video on Neil's timeline, with the assumption (some people disagree) that he's Kat and Sator's son. He has a very complex timeline because at one point, during the end battle, there are four versions of him coexisting.
I'm tentatively buying the Youtuber's theory that Sator went back to that day on the boat to die, 'because that day was a happy memory' or something like that, but I missed the plot point he made that Sator also suspected that day was THE day because on his first time timeline he heard reports of an explosion at that site (which if true, why didn't he investigate?). I'll be looking for that clue. I still don't totally understand why he didn't meet himself if they were both on the boat. I know the boat is big, but still.
All this just really makes me want to watch the movie again and see if it makes more sense now.
- "The same idiots whining about cancel culture are the people who tried to cancel pretty much every video game, book genre, and RPG when I was a kid." - James S. A. Corey