" If a person wants to use the WiSee, she would perform a specific repetition gesture sequence to get access to the receiver. This password concept would also keep the system secure and prevent a neighbor – or hacker – from controlling a device in your home. "
I think he refers to having a system that, using this approach, turns on his shower when he enters it. If this cannot distinguish humans from cats, it would turn on the shower when a cat entered it.
I think that's a bad example. The typical cat would soon learn not to enter the shower.
If the system has enough lag, clever cats might dart in and out before the shower sprayed for a brief bit, so as to get some fresh water (which they like more).
One of my cats has actually done this a couple of times. He walks along the ledge around the bathtub and squeezes past the shower handle, forcing it away from the wall and turning on the water. It's a problem that seems to have solved itself, because it scares the shit out of him and he gets wet.
I think this is where AI comes in -- it should be possible for AI to discern meaningful/non-meaningful movements (based on size, speed, previous state, etc.)