Need help with enemy AI

K so I have a sphere which is the enemy and want it to look at and follow my first person controller. I got it to look at the target but i have no idea how i make it move. i want it to be like the monster in this video - http://www.youtube.com/watch?v=gWggVbFl2QI . I have this so far -

var target : Transform;

function Update()
{

transform.LookAt(target);

}

I tried the smoothFollow script but the sphere always stays behind the player

perhaps something like this is what you are looking for

var rotate = Quaternion.LookRotation(LookAtTarget.transform.position - transform.position);
transform.rotation = Quaternion.Slerp(transform.rotation, rotate, damp); 
transform.Translate (0,0,speed*Time.deltaTime);