Dwars, Civvie, MtPain, Decino, and Doomkid are my favorites. I feel as if alot of Doom content on youtube is clickbait-y though. I guess that just always happen when a game when it gets popular.
I guess forgotten isn't the right word. I often see people saying it's a cult-following like thing, where it was unpopular when it first released but gained fans later on. I guess that's true but I still don't see the N64 as all that great of a console.
I think it comes from the ending of Doom 64/lore stuff in Doom Eternal. Y'know with the whole "Doomguy has been trapped in hell eternally fighting demons" thing. I don't believe it myself but it's a cool idea.