Shardorne, yes, you are right. I'm not too sure about the warped or uneven disc causing Jitter, though. My extensive experimentation shows that it is not this slow visible-to-the-eye movement of the lens which causes the Jitter one hears. Indeed, you can even put your finger onto a turning disc and you can cause a lot of low-frequency vibrations that way, but it isn't audible. What is audible then is if you go too far and cause a digital error. But Jitter itself is of a much more high frequency nature, as you say, such as from electronic oscillations and RF noise induction and the like.
Liudas
Liudas