Do you mean a single-episode treatment covering the entire history of each of China, Japan or WW2? That's a big ask, because it would be impossible to do justice to the subject without the thing running to series length. I suppose you might just be able to squeeze an overview of Japan or WW2 into 3-4 hours, but it would have to leave out vast amounts: for China without even Japan's dynastic continuity or reasonably compact geography, it would be a hopeless exercise.

Video can be good at relating individual themes or events, but for the whole story there's really nothing else for it but reading - and even then a single treatment gives you only one version of events and their cause and significance (unless it brings in multiple scholarly viewpoints, which is a good format but adds to the length), so you need a few different takes to begin to form a rounded picture (not all necessarily book-length - journal articles can be valuable for specific events or topics).

Each is really too big to take on in a single bound, so it's far better to tackle individual periods or themes ("events" not so much at first, they're better understood once you've the context). But video has its limitations, and I suspect you're drawing a blank in your search because here you're encountering those limitations.