Ability to resume viewing a program if you run out of time. Within X days of landing, login to a site using your record locator, flight number, seat number. The system knows what you last viewed and allows you stream it from (approximately) the point where you stopped.
This currently happens on at least some United streaming IFE. I watched part of a movie in flight in December. Monday, realized I hadn't finished it and loaded it back up. Picked up where I had left off 3 months ago. Not sure if that's the system or a cookie on my phone, but it was a pleasant surprise. I believe both flights were on Airbus.