The action stopped the harassment. This lady was training her bird using negative reinforcement. I also call it harassment training. This bird finally learned a peck on the lips was the only way to stop the harassment. Extending its wings would stop the rolling perch.
Negative reinforcement is used many times in dealing with caged birds.
When we chase our bird around the cage to get it on the hand, the bird tires from the chase and reluctantly gets on our hand. When it bites our hand, we may drop the bird to the ground, some even strike their bird to stop this behavior. Being chased, falling to the ground, or being struck may be something these birds will work to avoid in the future, maybe not. An animal trained with positive reinforcers will look forward to these interactions and work towards earning the reward. Parrots in the wild congregate and spend time screaming for many different reasons.