Imagine a world where your dog could play fetch by himself. It's not the future; it's this lucky dog's reality.
Instead of playing the usual game of fetch (when you get tired after 10 minutes), someone removed the human element from the game completely. His ingenious device allows his energetic pooch to play fetch all day long, for as long as he desires.
The best part is that the dog uses the device flawlessly. He puts the ball in the machine, cracks it back, steps off -- and the tennis ball goes flying. Then he retrieves the ball, puts it back in the machine, and does it all over again.
Maybe this guy could work on something similar for cats. Or kids.