Smooth Follow 2D simple tweak

I've applied this standard assets script to my camera and it's actually doing a good job but since my background texture is placed inside a quad that "follows" the player and not the camera at higher movement speed the camera gets too far or too much behind the player and gets out of view. Since I never programmed in JS I'd like to ask you how should I tweak this code to stop the script from moving the camera if the velocity is over (for example) 5f.

I tried to change it this way :

 var target : Transform;
 var smoothTime = 0.3;
 private var thisTransform : Transform;
 private var velocity : Vector2;
 
 function Start()
 {
     thisTransform = transform;
 }
 
 function Update() 
 {
 
         if(velocity.x > 5f)           //in C# I'd do it this way, but apparently 
               velocity.x = 5f;        //if velocity gets past 5, it doesn't remain 5
                                      
 
     thisTransform.position.x = Mathf.SmoothDamp( thisTransform.position.x, 
         target.position.x, velocity.x, smoothTime);
     thisTransform.position.y = Mathf.SmoothDamp( thisTransform.position.y, 
         target.position.y, velocity.y, smoothTime);
 }