Re: Nice video.
All the tail fins are pre-painted in airline colors. I know this for a fact as I was at 787 assembly in July*. The reason is crystal clear when you visit - it is a great PR stunt showing off all their customers. The reason for the re-spray is that the white coating is not actually the final 'paint' - it's a UV protection coating/primer for the carbon fiber body....
*If you are ever near Seattle, Washington (and you are even remotely interested in tech), you owe it to yourself to visit Boeing assembly in Everett. It is one of the most impressive things I have ever seen in my life and they give tours seven days a week.