Looks like a pilot induced oscillation. The 320 is known for such possibility.
Should a gust or turbulence move the aircraft in any way from its original attitude, the aircraft will automatically recover (no vectors were given by pilot). If, however, the pilot is reacting to such an attitude change through a control input, the aircraft will assume the intend to be from the stabilized attitude, hence correct for the attitude change due to gusts plus the control input of the pilot. This “overreaction” of the aircraft leads to an opposite input, thus starting an oscillation, or “chasing the aeroplane” as it is known.
I wouldn’t pay too much attention to the sound in this clip; there are too many factors which will lead to a misjudgement and conclusion