Easy but a good idea

An RFID tag you carry arround and when you leave the room it reports back to a USB device and pauses your show/movie. good for people who do stuff while watching tv and get distracted if it is a good show. Once you return it will play again. Bluetooth may be a better option although could be a problem since it goes through walls. With bluetooth however, you could do it with a cell phone and no additonal hardware would be needed.