The figure: Both electrons lie on the z-axis. From the figure, we can see that rotation around the z-axis would change nothing. So there is axial symmetry about the z-axis.
The formula: The assymetry parameter eta which is given by eta=(V_xx – V_yy)/V_zz will be 0 since V_xx = V_yy. This is representative for axial symmetry which was explained in the video.