I have posted images from movies in my questions before and always had this question in the back of my mind. I've just came across this OP's answer which included images from the movie The Martian where they did include a fair use claim at the end of their answer:
All screen shots are Copyright (C) 2015 20th Century Fox, used here under the Fair Use provision of U.S. Copyright law.
- Can this really be a legal countermeasure for such situations?
- Should we make it an automatic postscript for posts including images from movies where the OP has to fill in the name of the production company and the production year?