What Really Happened Here?

I have watched this video a dozen times.  All of the media and people who comment say it was a pilot at the controls.  It is possible I guess but as most pointed out it seems like the situation should not have ended this way.  I noticed the upper cowlings were removed, meaning to me, That possible it was doing a maintenance run.  If so is it possible the operator could have been a mechanic?  The other reason I ask is because the person who ran out the door was trying to give instructions with hand signals.  If it were a pilot then I can imagine the person would not have felt the need to give hand signals...  It's just me thinking out lod and getting some opinions.  I showed this video to our mechanic as a reminder of how quickly things can go wonky....

Thoughts?