From the YouTube description:

First step towards a homemade 3D printer. This is the insides of an HP1360, the paper feed encoder is being used to drive a stepper motor to move the gantry. The encoder is decoded and divided by a parallax propeller microcontroller that also detects the paper feed and ignores other paper feed motor rotations. The gantry is moved by a cable drive to be replaced by a belt.

Homemade flatbed printer – [via] Link