Flesh it out a bit.
It's too short and fast to tell what's going on.
I played Duck Hunt constantly when I had a Nintendo and I still had trouble figuring out what was going on until the second time around.
It's an OK concept, but you need to make it longer to establish a "plot" so that even people not familiar with Duck Hunt will understand the joke on the first viewiing.
EXAMPLE: Show a duck flying and the gun shoots and misses three times and have the dog laugh all three times. It'd build up to more of a punch-line.
Plus, it'd be funnier if the dog looked more hurt. Add some blood or make him all black like when a Looney Tunes character gets shot. Or SOMETHING.