I built the same thing about a year ago - animated jigsaw puzzles that are setup as "cinemagraphs", aka seamless repeating videos. It lets you upload your own GIFs/MP4 files as well but includes about 7 original ones.
It's a homage to one of my favorite games as a kid (the Island of Dr Brain). One of the stages in the game was a jigsaw puzzle of a lagoon with animated flamingos.