Hello and welcome! Kiwi is gorgeous and in my opinion this seems like normal (but slightly obsessive) behavior for a macaw. Does she do it all the time, or just when you approach the cage? It does not look aggressive, more like a pacing bird that has been used to being locked up and doesn't have much room to do much except pace along the perch. To me, she seems active and healthy in the video, possibly it is a behavior she has learned over time to release excess energy.....but I will let others with macaw experience chime in here.
She just stared doing this about 2 weeks ago. From what I understand, she was not let out of her cage at all for most of her life. We are getting her a new cage soon but she will be out for most of the day and her new play gym is being built this week. I am new to macaws and have had wild caught quaker parrots warm up to me faster than this lady. So all of this is quite new to me. As long as she is ok I am good with her being a little quirky.
I am wondering what I have done to her.
I would agree Kiwi's pacing behavior is fairly benign and may be symptomatic of a long-term cage-bound situation. The question of shadowing is fascinating as many birds are keenly aware of the shape and will interact. Been meaning to start a discussion thread! Might you experiment with eliminating the shadow if possible? Even if Kiwi paces in the absence of a shadow, there may be an expectation of a sudden emergence?
You likely have no idea of the "baggage" Kiwi harbors from prior home(s). Parrots have very long memories, and seemingly minor incidents can take years to eradicate. Not your fault!
