Increments of instability in capillary waves relevant to the bending–deformation mode on the surfaces of a conducting charged cylindrical jet of the ideal incompressible liquid moving at a constant speed relative to an ideal, incompressible material dielectric environment have been studied. It was shown that, although the bending–deformation waves are the last to be excited, after the axisymmetric and bending waves, their increment is the largest. The entire phenomenological picture of the realization of instability of a jet in the mode of branching jets is determined by a successive excitement of capillary waves with various symmetries. It has been shown that the viscosity of a liquid is of primary importance in the realization of the mode of branching jets.