"g4_0111.mp4" appears to be a specific video file name rather than a widely recognized topic or public phenomenon. Because file names like this are often generated automatically by cameras, drones, or editing software, the "topic" can vary wildly depending on where you encountered it.
Many security systems and dashcams save files using a "Group/Channel + Number" format.
Occasionally, cryptic file names are used in "Alternate Reality Games" (ARGs) or "creepypasta" stories to make a video feel like "found footage" or a leaked file.