I get why people are happy that this video got taken down. But as a fan creator, this honestly terrifies me.
Do you realize there was nothing in that video that infringed on copyright except for Alastor and Lucifer themselves?
The music was original. The animation was original. The story was original. The other characters' designs were original. Everything was original except for the designs of those two characters.
So, by that logic, any one of us could wake up one day and find a huge chunk of our fan work gone simply because we used those characters.
Doesn't that bother you?