Although it is only 10 minutes long, the movie goes pretty fast, so get your slow-mo glasses ready. I can't remember how long the actual time spent was, but I think it was about 2.5 hours. The final illustration with all revisions totaled about a day.
So, if you have 10 minutes to spend and don't mind reading a few very quick captions now and again (sorry), take a look.
Here's the link:
Book Cover Creation Video