Did you see this file name on a specific or horror forum , or

The .mp4 suffix is a common trope in Analog Horror or ARGs (Alternate Reality Games) to make fictional scary stories feel like "lost footage" found on a hard drive. Stories often involve "extra" roommates who aren't human or roommates who have undergone a personality change.

Videos detailing a roommate returning from a trip (like an Ayahuasca retreat) with a completely altered, frightening personality.