What are the fortune teller hand motions over a crystal ball called?

I'm not sure about what the hand motions themselves might be called, but the act of divining the future is called "scrying". I think the reason for the hand movement is temporarily obstruct the vision, as to retune the frequency of the crystal ball.

Theatrics. It adds to the drama. Makes for a more interesting reading.

Nothing more than that.

Misdirection.

It's the same as a stage magician doing hand movements or using props to divert attention from how things actually work.

With a fortune teller, it's to stop you from realising the "crystal ball" is just a lump of glass or an old fishing float & that you are being scammed...

https://www.amazon.com/Japanese-Glass-Fishing-Floa...

There definitely was some word I can't remember.

They are called "meaningless mumbo-jumbo," a phrase also used to describe any sentence spoken by Donald Dump.