From what I have read, she has little cortex left now. The deterioration was caused by a lack of oxygen to her brain after the incident in 1990. The brain stem, which is still intact, regulates some movements. As for the videos, I can't agree with you, though I'd love to.
Why would Ms. Sauer lie?
This is the first I've read about Ms. Sauer, and I have no idea as to whether or not she did. There's no reason to believe that she did.