I wonder if the aircraft was flying cargo which shifted aft after takeoff. The nose was high as it descended before stalling and it sounded like full power being applied to both engines.
I agree, looks like a possible weight shift aft, and /or the seat rail came loose, and the seat rolled back. I think a weight shift is more likely given the video with the plane in a nose high condition mushing at the edge of a stall, if so, with the CG so far back, she probably had the wheel full forward and the nose wouldn't come down, not good. A vertical climb and loop if confirmed indicates a loss of control. Let's see what the cargo manifest was.
Very sad. If the plane climbed "straight up" for 800 feet (think that's what she said) the engine didn't die. Sounds more like some sort of control problem. Anyway, hate to hear this kinda thing - young gal.
