According to Matt Baume, the creator of the above video:
We’re meant to root for their downfall. But somehow these scene-stealers are more beloved and memorable than the heroes. And who’s been among their biggest fans from the very beginning? Hashtag the gays. But … why? What is it about Disney villains that’s so appealing to gay audiences?
Baume says that Disney's attempts to covertly exploit stereotypically gay tropes in their animated villains to make them appear more creepier actually made them popular and relatable to gay audiences. I personally think he has a point because I am a fan of Disney villains (particularly Yzma from The Emperor's New Grove.) However, whether you agree or not, his video is still highly entertaining.