Here's the breakdown:

Looking out the window: 22%
Sleeping: 6%
Hiding under tables: 6%
Interacting with other family pets: 12%
Consuming digital media: 6%
Playing with toys: 5%
Eating or looking at food: 4%
Climbing on chairs or kitty condos: 8%

Yes, that's only 79% of their time, but what do we expect from a cat food company press release? They also said this when asked if the cats will ever get movie cameras instead of just still photo cameras: "We are in the think tank now." Funny, 'cause regular people on YouTube tape their cats alone all the time. A very scientific search finds that cats spend their time doing the above things and more!

Above, a cat who has named himself Lorenzo talks to the camera about what it's like to be all alone.

This cat flushes the toilet over and over all day:

This cat, in time-lapse, defies the rules by sleeping:

These four cats both look out the window AND interact with each other:

And, best for last: this cat has a companion dog who gets food out of the trash for them to eat...the very second their owners leave:

What Do Cats Do All Day? Kitty Cam Has the Answer [AP/MSNBC]