Horrifying Zoom hack will deter you from ever side-chatting again

How does this work for any profficient computer user?

I dont move my shoulders when typing, all through hand/fingers... just double checked in a mirror... arm might wobble a bit but there's more movement from breathing.

I would understand it working if you type one letter at a time with one finger... or conspiracy theory scenarios where webcam embeds key presses in the video somehow and that gets picked up by the ai.