That is at best a vague post, but quite frankly useless. Without exact system info and exact details about your footage nobody can tell you anything. The pertinent assumption would be that your footage is one of those atrocious "hacked" MP4 files from a crappy cheap camera or a game capturing tool, but we can't be sure. Either way you need to provide much more info.
It IS from a game capturing tool. But what does the file need to be in order to work? What exact system info and extra details do you need?
Your game capturing tool is probably recording to a format that is not supported by After Effects. If you can try transcoding to another format. Do you know what that means?