> A claim in the video that I can't verify but makes economic/logistic sense is that the speed problem isn't the panels but the controllers.

I don't understand the claim. It is lacking in specifics. Are they claiming that electrophoretic materials (meaning the panels) can actually switch (meaning move pigments) faster than say x.y micrometers per second? I don't think that is true. The article shows that what Wenting did ("binary transition") is pretty much the same as what companies like Dasung did. Instead of trying to have grayscale, it is faster to hit somewhat-black and somewhat-white and give the illusion of fast movement than actual fast movement.