Thank you everyone for all the great suggestions.
After I read Richies comment on Meguiars plastic cleaner I remembered many years ago I had purchased some and went out to my garage and found the almost empty bottle.
Also, all the discussion about using very fine sand paper reminded me that many years ago I had cleaned/polished the headlight lenses of two Mercury sables I owned. The cleaning kit I used at that time used very fine abrasive sheets along with cleaning and polishing creams.
I never thought about using automotive cleaners for the Aerotrain window.
I did try the Meguiars that I had left over and it actually got most of the film off the window.
Not perfect, but very good. I can see the figures I placed on the back seats and it looks good again.
In the next few weeks I may try some very fine abrasive paper and see if I can make it look new.
Thanks to everyone who provided such great advice so quickly!