Ajax Issue

I keep getting an AJAX error when I try to upload a video. The error is shown in the picture below. In case you can't see the error, it says "An AJAX HTTP request terminated abnormally. Debugging information follows. Path:/file/ajax/field_video/und/0/form_uurU0zVFoi1Znx-MI75J59UV_pkkNkVtVoA8ul5oQXU StatusText: n/a ResponseText: Server Error 404 - File or directory not found. The resource you are looking for might have been removed, had its name changed, or is temporarily unavailable. ReadyState: undefined

Any hints or tips as to how I can fix this?