I had this near exact situation happen. I turned around and in a calm tone told her “I need to to stop trying to do my job over my shoulder and if that’s an issue I can get my director to come and resolve this for you” (my it director and her were buddies) she became silent in shock I assume. Resolved the issue a minute later (video feed issue). Walked back to my office and got fired for my comment 2 hours later.