Matt Hirst couldn't figure out how his pets Dexter and Gizmo were escaping the kitchen while he was at work, so he set up a camera to spy on them. If you are in a hurry, skip to about 1:30. There, you'll see the cat use both paws to turn the doorknob!
When this breakthrough spreads to other cats, we're all in trouble. It will certainly mean my winter heating bill will soar, because cats only care about opening doors. They couldn't care less about being able to close one! Note to self: never position the cat tree near a doorknob. -via Arbroath