Son of Batman (Bat Transformation)

Once upon a time DC released some of the best superhero cartoons ever made (Batman: The Animated Series, Justice League Unlimited, etc.). Now the focus is on making direct-to-video animated films, and they're not as good. Son of Batman is overall mediocre, but it does have a subplot about members of the League of Assassins being turned into man-bats. Here's a scene of one of them reverting to human form, along with a slow-motion replay.