MP4 files recorded during a crash become corrupt, often.  What software will recover usable parts of the MP4 file?  

Today, I recorded video to MP4.  Then, I did it again.  Neither time involved any sort of crash.  Nice.  However, the first video is playable but the second MP4 file was not.  

There was no loss of signal and no battery or link failure during either flight.  There was not even a rough landing.  I shut down video upon landing, if not before.  

I have tried recovering missing content using VideoLAN with zero success.  As far as I can tell, the software is worthless recovering MP4 files.  I need a better solution, if I don't want to fly a few thousand miles now and then to re-visit my flight plan.  

In an effort to provide full disclosure, it is possible I shut down the Phantom before shutting off video.  I don't think that is the order of things but I'm allowing the possibility.  

Normally it is as you say, caused by turning off the phantom while its still recording, so not giving it time to finalise the recording.
The manual tells you how to recover the file.
Turning the phantom back on and waiting a minute will normally recover the last file on the memory card.

Part of the shutdown procedure when recording video it to always stop the video recording prior to shutting down the quadcopter proper.

That did the trick.  
Reviewing the video, I landed with the quad's shadow in view but I don't see any finger shadow poking the battery button so maybe something else happened.  Or not.  

But that did the trick.  Video has been recovered.  
Now, to see if I can get the same action out of the few others that 'couldn't be recovered.  

Thanks!