Very interesting! I've never tried scanning a book, but this looks like a fun project.
In the video, you're manually triggering each camera. Can't this be done remotely somehow? Also, are you recording the images to the camera card for later transfer, or directly to your computer via USB?
Hmm...after a little poking around, I found
gphoto, which seems to do both these things, but unfortunately the Canon Powershot A590 you recommend doesn't support remote capture operation.
Ken