I do the same thing. I have a collection of about 15 DVDs that I carry with me when I travel. I also own a laptop power adapter (obviously). I'd be happy to enter into some sort of exchange program, but I'm not sure it would work. It can be 6 months before I finally get around to watching any particular DVD; it can be a long time before all the conditions are right.
I find that I don't watch movies on flights very often because my car is usually parked at the destination airport.