Knot theory, entropy and maze solving are things most people don't know about though. If this critique is pointed at the Oppenheimer video because there was a popular movie then I would say that it's ok to talk about something trending if most of his videos are relatively niche.

I think you hit the nail on the head. I’m fairly knowledgeable in the natural sciences, but I still used to learn a lot from watching his videos. These days, more often than not my reaction is just “well thats obvious”. It reminds me of the MythBusters episode when they shot a ball out of the back of a moving truck, and when they confirmed the ball dropped without moving, Carrie just sarcastically said “Yay we did vector addition…”