Wow it looks like they've caught on to something. I've tried a few ~1.2 MB scans of film negatives and it shrunk the sizes 5x and 6x with no differences that I can see. When I tried smaller files however the difference got down to ~1.5x with some more obvious noise removal so I think it's just exploiting inefficiencies in how large jpg's are encoded.

I also love the sense of humor. "SEEMS YOUR PHOTO LOST SOME WEIGHT!"