"The Madness of King Scar" is a song that was based on a scene cut from the original Lion King movie that ultimately made it into the stage musical. One animator took the disturbing Scar and Nala portion of the song and imagined how it might have looked in the animated movie.
The full song is quite a bit longer and features Zazu and the hyenas, but animator Eduardo Quintana focuses here on the Nala and Scar bit, which is the creepiest part of the song.
Here is the original storyboarded version of the full scene:
[via Watermelon Animation]