Originally Posted by Intruder
Because they do whatever the computers tell them to do that instant.
It is possible the airplane was NOT in stable flight, but transitioning/turning/rolling. The computers will often have the control surfaces moving wildly in that case to retain stability.
I tend to agree. It looks as though the computers are already commanding her to go to the right, even though she still is in a left bank. Those rudders, apparently, indicate that, too.
I've seen it many times in the airplane I fly (B777). Even in cruise, perfectly levelled off, sometimes you see the flaperons up and down to correct a mild turbulence. Just the FBW system at work.