The “freeze” is when her legs go stiff and she is unable to walk forward. This is not fainting, when one’s knees buckle and collapse. Many of us have fainted, or have seen fainting, and know this is a different thing entirely. In Parkinson’s, the person has “gait hesitation,” where she wants to walk forward but is frozen in place due to spastic rigidity.
I see it quite clearly in the link you provided.