It’s a Mata Hari using an Arduino board to add features, modes and rewrite the rules.
Video description by PinballHelp:
This is an early look at a prototype pinball mod that allows a small microcontroller to hook into early Bally/Stern solid state games, and completely rewrite the rules! The technology is in the early stages but is really promising and there’s a good chance there will now be special versions of modified rulesets for most of these early solid state games. Turning these games from shallow into more complicated, multi-mode games, even with wizard modes, skill shots and custom sound. I am demonstrating an early prototype of the system. For more visit: http://pinballhelp.com