So in my opinion, the probable cause was an accidental spin due to poor pilot training and lack of experience.
Agreed. The pilot was messing around with slow speed and uncoordinated flight and for some reason did that at very low altitude. Sad.
http://imgur.com/a/q9oYM#0
#1: Ailerons neutral, right rudder and up elevator - exactly how you enter a snap roll or spin.
#2: Rudder neutral, left aileron and slight up elevator.
#3: Rudder neutral, left aileron and more up elevator.
If at the first moment the pilot lost control they put the proper recovery inputs in I don't think they'd recover. Shouldn't have been flying like that down low.