The "g" prefix followed by a four-digit number is a signature naming convention for video exports from security management platforms, most notably .
A file named "g9640.mp4" is likely a proprietary surveillance clip that has been converted or exported to a standard format for viewing on standard Windows or mobile media players. g9640.mp4
These systems typically record in proprietary formats like .g64 or .g64x to preserve metadata such as timestamps, motion indicators, and bookmarks. The "g" prefix followed by a four-digit number