1visualFXguy and Supers, Heroes, and Funnies will do a crossover
How close friends Matt and Asher (the creator of both shows, respectively) are, I'm surprised this hasn't happened yet.
M2 and the clones are a science experiment gone mad
1visualFXguy and Happy Tree Friends are set in the same universe
The frequent appearances of the HTFs makes this one plausible.
Zed and the Buckaneers is supposedly a rival to Creedence Clearwater Revival
Lily is a ghost in the ALF and Omega sequels
Since she died in the first one, she could either be a ghost or zombie and since she doesn't have her guts hanging out, she must not be a zombie.
Jim is a goblin
He is certainly a weird creature of some sort. I think he's either a goblin, demon, imp, troll, minotaur, or vampire.
In the 1visualFXguy universe, King Leonidas has a time machine
How else could he meet Scrat from Ice Age if 300 is set in Ancient Rome and Ice Age is set in, well, the ice age.
Why else would would Dipper let him borrow his hat?
Rooster is an alien dog
It makes sense because of how his eyes glow red and he can talk.
Mr. Mcgee dated Janice Joplin
Since it was confirmed that his name Bobby Mcgee, this one is plausible.
Raven is from the Town of Grove
The game Fate has a lot of demons in it and since Raven is demon, this theory makes sense. Especially when she does a direct imitation of the Fate narrators voice in the "Clash of the Teen Titans" poop.
The show will parody Norm of the North
Since it's already parodied Alpha and Omega several times, this isn't entirely out of question.
Gabi is a HUGE Family Guy fan
Since she sings like Herbert and frequently makes Family Guy references (more than any other recurring 1visualFXguy character).
1visualFXguy is a part of the DC Comics universe
Teen Titans and Harley Quinn do appear a lot. Plus Gotham City is mentioned in one video.
Arnold P. Moolah has since retired
The character hasn't appeared (outside of music videos) in a LONG time, so maybe he quit his job as a lawyer.