The porn video tag "fortnite-demi" refers to a scene that involves elements from the popular video game Fortnite and the name "Demi." In this context, Demi likely represents an adult performer or character who is engaging in sexual activities while either wearing clothing inspired by the Fortnite theme or in a setting that resembles the game's environment. The tag combines the interests of gaming and adult content, potentially appealing to viewers who enjoy both.