Watched this several times. Looks like:
A: the pilot slowed to Vmc or less, which would explain the roll to the left (left engine is critical on most conventional twin-engine aircraft)
B: the stall and Vmc induced roll occurred just before the exit
C: a Vmc induced roll does not require the critical engine to be failed. At 16,000', and at probably around 80kts, the thrust from the right side of the right propeller disc would be enough to cause this. And to a low-time pilotnit would be unexpected. Vmc demos are always done with the critical engine either shut down, feathered or set to zero thrust.
D: full flaps did not help the situation.
E: I'm not sure what 90 series King Air this is, but if it's an A or B model, they were woefully underpowered, which ironically would exacerbate this situation, especially at the altitude they were at
As Hydro said, if the pilot had simply lowered the nose, it would have dramatically helped.
R_Strowe