As a kid I loved watching spinning objects like tops and the reels of an old R2R rape recorder. I still love to rest my eyes on its reels and records on a turntable playing music (I still have a turntable, too).
I used to spin over myself vertically, starting sideways (what is it called? I still can do it), and spin horizontally fiercely with someone else while grabbing with my right hand the wrist of the left hand and with the left hand the wrist of the other person's right hand (the other person doing the same). Or, at home, I liked to spin all by myself, till my eyes moved horizontally back and forth and I felt dizzy...
Visual stims work similarly to other physical body movements, they stimulate sensory organs.