In Mario Kart 8/Deluxe, the VS Race mode actually has a hidden time limit of 10 minutes per race. After 10 minutes have passed, the race automatically finishes and whoever is ahead at that point is declared the winner.
If neither player touches any of the controls for the entirety of the 10 minutes, the game will declare the player whose starting position was closer to the starting line as the winner (seen with Luigi in the footage), as such making that player win without doing anything.
