A lot of the comments to the video on YouTube refer to "suction feet" and "spider cat" and that sort of stuff. They haven't figured out how she does this but she has and she does it instinctively.
It is clear from the beginning that Piggy is using the wall adjacent to the fridge to good advantage. She places her back against the wall as soon as she starts to descend.
She uses her strong legs to press her back hard against the wall. This creates a tension throughout her body and puts pressure on her paws that are in contact with the fridge.
This allows her to walk down the fridge and even stop half way and have a chat. You can see the same technique used by mountaineers climbing steep rock faces. They sometimes use indentations that are in the shape of a column of rock to shimmy up the mountain.
Here is the video:
For me this confirms what I already know. Cats are pretty smart. They can understand a bit of simple physics. I can think of a similar sort of thought process with my cat Charlie. He has three legs so he has to figure out how to do things that other cats take for granted.
One of the difficulties that he has is jumping down because his single front leg can't take the pressure on landing. He twists his body as he jumping down and lands on all three legs simultaneously. Neat solution. I have also seen him jump from a wall onto a sloping tree and then to the ground to get off the wall. He used the tree in an elegant way as a staging post in the jump down. These things come instinctively to him which makes me think that there is some pretty sharp thought processes going on.
