Brian says that he lived in the apartment 3 years ago, so this happened over a longer period of time. This would line up with other recurring "demons" in other videos. In This One's for the Swedes! video [https://youtu.be/9nNW54MP98c?t=45], about 4 years before this video, Brian says thanks in Swedish, but upon closer examination, the words actually mean "My life has been a series of existential torture. I was meant to be a beacon of light in people's lives, but now I'm exposed to the whims of a madman kill me kill me kill me kill me kill me kill me kill me." In Brian's Autobiography video [https://youtu.be/z5B_HRBDwvg] Brian mentions that he sold his soul to a demon to see how he will die. He finds out, but the demon still lingers. In "how to make jorts" [https://youtu.be/Sx3ORAO1Y6s] the demon possesses a pair of jorts that Brian is trying to make, which he gets rid of by cutting the jorts. The demon gets angry, and tries to trick Brian into giving him his personality along with his soul, which was in the skipped verses in "Have you seen my laptop?" [https://youtu.be/YV__C64Ni50] The demon the needs the body, so it slowly takes over Brian by making him go paranoid and insane by giving him free money and eventually taking him over, as seen in the woods in Nebraska. The Brian at the end is the demon, now a full replica of the original, with soul, body, and personality.