A or randomized filename generated during a download or file conversion process. A specific, obscure filename from a local system.
you saw this name (e.g., in a download folder, a specific app, or a link)? ggggggggggggggggggmp4
Because ".mp4" is a standard video file container, it is possible this is a corrupted or randomly named video file. If you can provide more context, such as: A or randomized filename generated during a download