Boeing a sponsor of the Seahawks, and the aircraft is a freighter owned by Boeing and used for testing (equipment? possibly used to haul parts?). The livery doesn't appear to be just for the Superbowl, so it's probably a permanent marketing/PR piece for their local city.
I wonder how much that really costs, though. The plane has to be painted one way or another, so you're paying for the design (which doesn't seem too involved here, since it's borrowing elements from elsewhere) and whatever extra work is involved with painting a more elaborate pattern.
Still, not entirely zero, you're right. I imagine the extra cost for the paint job came out of the marketing budget. Probably well worth it.
While bare aluminum saves weight, the TCO is higher:
"While the lighter weight of a polished airplane saves fuel costs [...] this savings is more than offset by the higher cost of washing, polishing, and painting a polished fuselage throughout its service life. The net operating cost of polished airplanes, calculated as a percentage of the total operating cost, is between 0.06 percent and 0.30 percent more than the total operating cost of fully painted airplanes."
http://boeing.mediaroom.com/2014-01-29-Boeing-747-8-Freighte...