Conversion of part files to mp4 file format

If you are looking for a way how you could convert partial downloaded file - part to mp4 video file format (for example from Firefox web browser ), then you most like won't find it, because it is not possible. You might try to rename part to mp4 and playback it in some media player, but it will be corrupted in most cases, or only parts will be watchable. You need to re-download the file again. If some cases you can try to re-download the file again and hope the download will continue and you won't need to download the file again.

Open PART file    Open MP4 file