Thank you for these instructions! Works perfectly! I just used one small variation. Once I had the mirror exposed, I took a Moistened Eye Glass cleaner (the type you can get in any drug store in the small packets to clean your eye glasses), folded it over the end of a 14" ruler, and holding the ruler with my fingers while also holding the folded pr-moistened eye glass cleaner, I lightly ran the end of the ruler up and down the mirror until the film was gone. It only took a couple of passes.
It worked a treat.