In this episode, Paul teaches viewers about the hopper, a device used to transfer materials it recieves into a chest. Later, he uses the knowledge to construct a semi-automatic netherwart farm on the top of Tower of Power.
The hopper is crafter with five pieces of iron (placed in almost a "v" or "u" shape) and one chest in the center. Once placed, items tossed into the hopper will automatically be stored inside (you can also insert items by accessing the hopper's inventory). If a chest is underneath the hopper, the items will automatically drop into the chest.