Demon Dog is a screamer video made by Dane Boedigheimer or known as Daneboe, first uploaded in 2009.
The video begins with footage of Dane's dog, Charlie, looking around the room, along with a header that says "Charlie Can Make An Angry Face". Offscreen, Dane himself (who's recording) is trying to encourage Charlie to make the angry face. It takes a few attempts, but after Dane says "Come on, make the angry face. Angry!!", Charlie's face becomes very demonic and he lets out a loud roar, before turning back to normal. Dane then rubs his head, happy that he successfully pulled it off.
NOTE: The following video contains a screamer!