No video online uses this DFly version as far as I can see and in the manual I can't see anything similar to the DI2 setup my wife's FELT has. It's an Ultegra DI2 with external battery. There's a cable from each shifter to a SM-EW90-B and then the middle cable from this 3-port box runs into the frame. On the back there's a cable coming out of the frame for the rear derailleur, another for the front derailleur and yet another for the battery.
Any guesses on where to install this?