From what I saw I would guess it was a trim issue . The seat movement could also be correct of course but the pitch up to 200-300 feet appeared to be speed driven not a sudden pitch up followed by a stall and left wing down. The aircraft had very little forward speed when it hit as witnessed by the ground strike and position of the prop which detached and had severely bent blades in a rotational sense. As for the engine noise I put it down to the Doppler effect of full screaming 206 on takeoff but decelerating speed followed by a thud!