"Ending Theme - Super Mario World" is a high quality rip of the ending theme music from Super Mario World.
This rip features a remixed version of the theme song from the TV show Jeopardy!, which then turns into the theme song of the TV show The Simpsons.
The video in the rip shows an image of the ending of the game "Super Mario 64 Genesis", with Mario, Peach and Luigi from the Super Mario Bros. series. Then, both Mario and Peach's faces turns into Luigi's, and the text "YOU FUCKING IDIOT" shows.
The video is a reference to a stream by famous Twitch streamer Vinesauce Joel about a Super Mario 64 bootleg for the Sega Genesis. After completing the game, Joel received a bare-bones and disappointing ending, leading to Joel editing the ending using his streaming program's capture and text tools to read "YOU FUCKING IDIOT" and replacing Mario and Peach's faces with Luigi's.