Responses to videos by the general public are generally non-existent / minimal - don't be put off by that.
You could use it as part of a larger game - for example take care of your dog - so you'd need to feed it, walk it, pet it etc.
Or pet the dog to calm it down - for example a person walks by and you can just lightly pet it and it will stay - if a cat walks by the person has to furiously pet the dog to make him stay etc.
Or offer it as a stress-relief app - pet the dog until you feel calm again. Have a calm-o-meter on the side ...
I think it's a cool concept - just needs to be fleshed out.