Yup that’s what I found, a hard core wrapped in yards of very thin rubber bands. Curiosity got the best of me and I broke into one when I was a kid. (Fun times)
And that’s some pretty sharp blade in that video, damn!
Go back a little more, and the core of some was a small rubber ball filled with an oily liquid that you did not want to get on your skin. Others had a steel ball at the center.
I used to work at a golf ball factory in Massachusetts. It was cool because I got to tell my friends I worked in a bouncy ball factory, and I got to do some “product testing” on Wednesday afternoons. (I got paid to go golfing). They had a dual core interior so that when you whack it with a driver, it offers more compression (aka bouncy effect) and less spin, thereby going further and straighter - but on your short game (where the angle of the clubs is greater), it would not compress as much, and instead offer more spin - thereby giving you more control as you approached the green. Lots of fun science is hidden in golf ball tech. Including the dimple pattern - which is kept incredibly secret, which I always thought was strange because…couldn’t a competitor easily copy it by buying a golf ball?