There's a reason it takes a rare power-up to turn into a cat in the Mushroom Kingdom -- they're just too powerful. While the plumber is away, Super Mario Cat saves the day.
Youtube's Mr. TVCow shot a bunch of footage of this cat, and then spent hours adding CG Mario scenery and sound effects. This seems like a perfectly valid use of one's time to me. Makes me wish I had a camera and a cat.
A good cat, I mean.