You can apply window film on double pane windows you just have to be aware of the heat absorption percentages. some films absorb more heat than others ( depending on darkness,reflectivity or metal properties) what happens is the inside piece of glass absorbs the heat and increases the air space between the two panes causing the glass to bow out. The normal expansion is OK, but with the increase from higher absorption the glass tends to bow more than normal. Now your inside pane has film on it and that film restricts the amount the inside glass can expand causing all the pressure on the outside piece to over expand causing breakage or seal damage. The white out film or frosting as it is called is not an issue due to low heat absorption, but you will lose any vision in or out of those windows. Some have said they were able to get it at some stores if you have a problem pm me maybe i can help you out. hope this helps clear things up a little Mike