Footwork while standing still

I have noticed that a lot of professional, and really good people jump, or move their foot when they are practicing consistency and standing still. what exactly are they doing jumping a little bit back and forth or moving their feet? This is the perfect example http://www.youtube.com/watch?v=WexWgPqoNF0 Skip to 3:00

i know that this is a little girl, but she looks like some pro trained her. and this is also a good example: http://www.youtube.com/watch?v=77sBz3vdW3U   skip to 1:30 

I know that this is looping, but i see it forehand drives a lot.

Hi Karlo,

I think this is a n exaggerated way of hitting.  I think stillness is more important to make sure you are keeping your eyes still and your body is balanced.