In many technical or security contexts, a filename like this often represents a (e.g., footage captured between midnight and 6:00 AM). Because the "mkv" format is a common container for high-definition video, it is frequently used by security systems, screen recorders, or media preservationists.
The filename does not appear to be associated with a widely known viral video, ARG (Alternate Reality Game), or specific public blog post.
If you are referring to a specific creepypasta, mystery, or a file found in a particular online community, could you provide more of what happens in the video? Finding the right details will help me track down the exact story or "lore" you're looking for.