A quick look shows that:
1. Flight control systems were working at least to enough degree to maintain basic flight stability and control as enough control authority seems to be still there in both longitudinal, lateral planes . Though as I watched more closely, it seems there is loss of longitudinal control authority in inverted position. But that may be pilot being disoriented or encounter with ground heated pocket of extremely low air density. Its speed may not have been enough to provide the required longitudinal control authority in that inverted orientation and encountered heated low air density.
Even though Flight Control authority is there, again a bit more careful viewing shows, there is some loss of control authority as pilot fails to pull up in inverted position which I think he was suppose to do. It may be due to pilot error or due to loss of lift due to lower than expected air density gradient in turn caused by temperature gradient due to the desert heat. That is close to the ground, decrease in air density due to ground heating may have made expected recovery hard. There is significant loss of pull up authority while in inverted position. Engine failure leading to Loss of thrust even partial can do that too and so does obviously loss of power to the control surfaces.
In any case, descent was too rapid way above the effectiveness range of coupled flight control system as a whole. There was NO way pilot could have controlled the descent rate with a delta wing optimized for speed at such low speeds with given control surfaces even if everything worked. It may have been that the pilot simply misjudged the altitude or even orientation due to of g-forces impacting his brain regardless of training.
2. At some stage just before there is pilot effort to level the aircraft where questionable movements are seen. That shows either problems with instruments, pilot confusion, disorientation or just extreme stress that led to that effort to orient the aircraft into hopefully safe "crash landing" position. A much better decision would have been to role/orient the aircraft immediately for safe ejection and eject. But I think there was sincere attempt to safe the aircraft.
Still pilot error does seems to play some role here. RIP.
Being under pressure to show case what may have been too risky also may have played some role.
Caution: My knowledge of aircraft flight dynamics is mathematical and certainty NOT as a fighter pilot and what G forces do to them. NOR how much risk they take for "airshow maneuvers". So it may all turn out to be too mature at this stage. Its hard to judge from the video. But I still think pilot error was partially to blame here.