In our bodies, we have arteries (shown in red) that carries the fresh blood away from the heart and lungs to the rest of our body.  We also have veins (shown in blue) which carries the blood back to our heart and lungs to get more nutrients and continue the cycle.

The video shows the one-way vein valves in action.  When the muscle is squeezed, blood is pushed forward, then the valve shuts preventing the backwards flow of blood.  Our bodies were designed for us to move.  Walking and moving our calf muscle is the primary reason blood moves in our veins.  Sometimes the calf muscle is called the accessory heart.

The arteries have a thick muscular wall which beats all the time.  Therefore, you can measure your pulse which is often measured at your wrist or neck.  On the other hand, veins have a thin wall and do not beat.  The veins stretch with the increasing volume of blood.  When we contract the nearby muscle, this muscle will squeeze the vein thereby pushing the blood forward.  We have a series of one-way valves in our veins to prevent the backwards flow of blood.