Small piece of hardware connectable to TVs, projectors, etc., for playing video files. Commonly used in galleries.
Doing some research on making an easy-to-use alternative.
Base point of comparison is the Lūpa. It's very plug-and-play—video loops automatically, and can automatically sync video between multiple boxes—based on a RPi, but is very expensive ($300)!
Some links for now, will add notes: