On certain aircrafts, that seems to be the case!
Delta Airlines is currently upgrading part of its fleet to have better in-flight entertainment systems. If you find yourself in an aircraft with the new touch screen in the back of the headrest you may be in for a treat. It seems that who ever installed the software missed the part where you have to pay for the premium items like movies on domestic flights! Chances are that this will be corrected as each aircraft is taken in for routine maintenance. So the next time you sit down in a newly renovated Delta plane take a moment and try and watch a movie or play a game. If it lets you, it’s free! (This has been observed on the Boeing 737 and 757 aircraft.)
Note: If you find yourself NOT on an aircraft that offers free movies, be sure to browse the FlyInStyle App. It’s always free and always fun.