That is the video I watched. It does not show that Fields was grabbed. I do not even see an indication that she was grabbed.
Have you watched the video? Lewandowski walks right by her. He does not slow down; she does not wince or flinch, pull away, or stumble.
His hand is extended back toward her as if he is brushing by her, turning his right shoulder back to do so.
The video completely disproves her narrative.
What do you see there?