pinster68 (here on pinside) ran a test with one of the more expensive UV films a few years ago and the results weren't very good (red construction paper; control piece inside a pinball machine cabinet, one piece near a window lined with the uv film, and a 3rd piece near a window with normal glass). the differences between the UV film and regular glass were noticable but both were extremely faded compared to the control paper
https://pinside.com/pinball/forum/topic/uv-window-protection
I actually line the windows of my "game room" with this:
http://www.homedepot.com/p/Owens-Corning-FOAMULAR-150-2-in-x-4-ft-x-8-ft-R-10-Scored-Squared-Edge-Insulation-Sheathing-45W/100320352