I'm glad my cat that's fascinated with flushing toilets hasn't figured that out, my water bill would be way up! When my older son is home from college he humors the cat by letting him lead him into the bathroom and flushing the toilet for him. The cat watches the swirling water the same way the one in the video does.
Actually, cats all seem to regard toilets as magical fountains: the humans foul them, but the water returns to being fresh! I've never known a cat that didn't prefer a toilet to a water bowl.
Cats usually prefer toilet water because it's the one place in a home where the water is cool and is being refreshed/replaced repeatedly throughout the day.