Large flat screen TVs are pretty cheap these days.. Same with small ceiling projectors and screens. Just sayin'..
Why cover up the interior of a window with $20 worth of plastic film to look at all the time, when you can snag a used flat screen or 3 off craigslist for a little more to use instead?
Then you can pretend like your still looking out of your NEW window (you could even glue trim over the screens to look like real frames with glass panes), at that nice new relaxing waterfall you installed in your new backyard, minus the neighbors! They make programs to emulate "windows" btw.
Besides that, the TV or whatever will probably insulate from thermal losses (better than a layer of film?) that would normally happen through most kinds of window walls.. Maybe enough to make up for the energy needed to run it, who knows? lol..
Like this, but covering an existing window instead. Maybe the TV/s will stuff right in with minimal work, and just fill the gaps? Or find one that covers over the whole window?