Whatever it is that might be there is probably what allowed her to SCROLL for what she needed, while everyone was concentrating on Trump speaking.
She’s getting ready to memorise the reply to the next question.
What I see are NOT involuntary hand movements. Anyone who has ever used a laptop will know what she’s doing:
https://www.youtube.com/watch?v=KTvoLoQVzKM
Click on this link for a larger view Hillaroid's Podium
This shows how the podiums differ in height.
Click on this link for a very large version Hillaroid's Shorter Podium.
And finally I thought I would point out there is no ear bud.