This timelapse was filmed from the inside of a watermelon with a GoPro. The maker of this video sliced a small hole in the melon, put the camera inside, and let it film the decay over a period of 128 days.
The most alarming part of this video is the way that the inside of a watermelon resembles a rotten looking mouth. This would be a great way to make a monster mouth for a DIY horror film. It's going to be a while before I can eat a watermelon again.
From YouTube: "Usually I film stuff from the outside, or I put some other stuff in things, but this time I decided to put a camera inside the subject itself. I filmed the inside of a watermelon for as long as possible, capturing its collapse and the entire decomposition process until it dried out completely."
See also: Behold the hand-crocheted watermelon themed bikini