I only watched the video briefly, but basically every modification of the game is sanctionable. However, I believe that such modifications are more difficult to follow and therefore more difficult to sanction (-> clientside).
[Selling] FORTNITE ONLINE SKIN CHANGER 08/17/2018 - Fortnite Trading - 0 Replies Selling fortnite skin changer.
Hi, I'm selling fortnite skin changer, you can use in lobby and you can change skin in which you want! That are unrelased too!
I can show you it in live if you will be interested
Screen:
https://imgur.com/a/qrbgaCD
Price: 60€