I don't remember the name of the machine my vestibular therapist used, but it was not a treadmill, per se. It went somewhat around me, and the screen had many different programs including objects that were coming at me which I was supposed to avoid without losing my balance. The first time I did it, 71 objects hit me, and I avoided only 29. I also fell 5 times losing my balance completely. Fortunately, I was hooked to a halter vest with ropes from above. So, even when I fell, I did not fall far, and I did not hurt myself.
The machine my vestibular therapist used had panels on the floor which could go forward and backwards. When I stood on these panels, and they lifted my toes and then went back to normal and then lifted my heels, it was challenging to keep my balance. But week by week I kept improving. The last time I saw the therapist I avoided 100% of the objects coming at me on the screen, and I did not fall one time. My overall score went from a 28 to an 83 by the time I finished. That score would not be great for a young person, but it was very good for someone my age.
So, I don't know if it is the same machine your person referred to or not, but if so, I would not call it a treadmill. It was more hip and ankle movement than like walking on a treadmill. But the machine was designed for those with vestibular issues, and none of the regular physical therapists I saw had anything like that. That's why it was well worth it for me to drive over an hour to see the vestibular therapist. I can walk now without using a cane and without losing my balance. That was not true before my vestibular therapy. But, as they say, bjhk, your mileage may vary.
I wish you well in your journey!
Don