When the plane noses down and begins its uncontrolled dive, the passengers lunge forward in their seats. A diving airplane is accelerating forward so passengers will be forced backward in their seats just as passengers in an automobile are forced backwards when it accelerates forward.
The narrator said that once the threads on the nut were stripped the jack screw could no longer turn. In fact, the jack screw could turn, but the nut would not move because the thread were stripped and it would slide freely.
The narrator says that the whistle-blower who knew about the jack-screw problems and lack of proper greasing happened "In December 1999, over one year, before the crash." However, Alaska Airlines Flight 261 crashed in January of 2000. He should have said, "One month before the crash."