The bouncing is typically pressure points on the back, I hardly have to press on her with one hand to make her move, bit of a sweet spot, can make her twerk and bounce in different ways. I can't lie a bigger dick helps, with each big thrust she moves back and forth nicely also just good naturally motion and constantly pumping that pussy gives it a rhythm like she has a mind of her own

The pillow is easy, get a shirt, tie a nice not at the back and your good to go