VLC Media Player is often the best choice if you are having trouble with specific codecs.
Since it is an MP4 file , it is a standard digital multimedia container. You can open it with: Windows: Windows Media Player or Movies & TV . Mac: QuickTime Player . g371_001.mp4
Many DVR and NVR systems (like those from Lorex or Swann) use alphanumeric prefixes like "g" followed by a channel number and sequence to name exported clips. VLC Media Player is often the best choice