Dogs don't really get technology. No matter how many times they see another dog on the TV, they never realise that it's not actually in the living room.
It's one of the great joys of having a dog - watching them get confused by modern wonders. This particular dog fancied a game of fetch and thought he'd be able to catch the darts that were being thrown on TV. Luckily for him, the sharp objects stayed firmly inside the magic box.