That's miles ahead of the home made hay bale tossers they used to use around here. If I remember correctly those had a yardarm with ropes and hooks for a man to engage a bale on the ground then the arm was yanked upward to toss the bale up to the guy stacking on the truck. The winch that lifted the arm went to a pulley mounted in place of the wheel on one side of a salvaged rear axle. Somehow a quick stab on a brake pedal locked the opposite side of that axle, reeling the winch in suddenly. The whole mess was on a stripped car chassis that had the winch operator and a separate driver. Pre-OSHA obviously!
Here's a photo of something similar. This one looks to be factory made.