Yesterday I put that 'Roll-On' plastic on the two big windows in the living room (inside). I bought it last year or the year before but never put it on. This year I finally decided to. It is the "Duck" brand Roll-On Window Kit, Premium Insulating Film, 62" high x 200" wide. The one roll covered both windows - with just a little left over.
I actually have to say that it went on much better than any I've done before. You definitely need to allow the extra 2" on each side though. It probably only took me about 30 minutes for both windows. I cleaned the windows, cleaned the window sills, then used the provided alcohol swabs where I was to put the tape down, unrolled it, taped it down, used the blow dryer to take out the wrinkles, and... vwala... it looks pretty nice, if I do say so myself.