My best wishes to the injured, hope they will all recover
The video-link does not work for me, but I´ve watched it on TV yesterday evening. It´s always scary to see what will happen next, and not to be able to do anything about it.
The pictures are really interesting, I think I will use them for one of my next lessons. You can clearly see the rudder deflected into the turn, opposite aileron and elevator pulled back. Looks quite like the aerodynamics book´s best way to spin an aircraft.
I hope we will know the whole story soon, looks like some mechanical malfunction to me, maybe stuck left rudder ?