A dynamic stretch is a stretch where motion is involved. The end position is not held. Ballistic stretching is a form of dynamic stretching that uses even more effort to force the muscle beyond it's limits (more intensive & more likely to lead to an injury). A dynamic stretch is not necessarily a kick like shown here. Walking flat stances or lunges also stretch your muscles dynamically. Exercises like the one shown above can also be ballistic stretches. Find exercises and more information about stretching at stretching main.