Ggggggggggggggggggmp4 99%

A or randomized filename generated during a download or file conversion process. A specific, obscure filename from a local system.

it is supposed to be (e.g., a video from a camera or a download from a website)? 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