The ones I have are 304x640, which came out of an .epub file, of which I don’t even remember where it came from. They look decent when upscaled, but still not amazing.
My .epub file is 519mb, and according to the Apple Books website, their version is 1.2gb, so it seems that the video files would be a lot better.
I can’t buy or download that version of the eBooks (looks like they aren’t avalible in Australia?) but it looks pretty confirmed that the video files would look a lot better. Best way to get it would be to download it to an iPhone/iPad/iPad, and sync it to a PC/Mac, and then figure out how to extract it from there.
Hopefully someone is able to get that raw ebook file, I’d love to crack into it and get the higher res video files. Would do wonders for many projects around here.