Always maintain an original copy before attempting to use "repair" software, as some tools can further damage the data.
The index (moov atom) of the MP4 is missing or damaged. fsdss206mp4 fixed
If the file was interrupted during saving, the "header" (which tells the player how long the video is) might be at the end of the file or missing. Always maintain an original copy before attempting to
The most common "fix" isn't repairing the file, but using a player that can read damaged or complex containers. fsdss206mp4 fixed