rigidbody2D.MovePosition() Can't Found

There is no RigidBody2D.MovePosition() method. Link to docs

But it would be very useful to have a method like this that avoided the problems of Transform.Translate() when applied to a RigidBody.

The advice on this thread is now out of date. MovePosition is a non-beta function in the standard release. (documentation)

Using this function is different to how it is explained in the video; just following instructions will lead to compiler errors. Following the guidance in documentation I have made the following code which operates as expected:

 using UnityEngine;
 using System.Collections;
 
 public class HatController : MonoBehaviour {
 
     public Camera cam;
 
     // Use this for initialization
     void Start () {
         if (cam == null) {
             cam = Camera.main;
         }
     }
     
     // Update is called once per physics timestep
     void FixedUpdate () {
         Vector3 rawPosition = cam.ScreenToWorldPoint (Input.mousePosition);
         Vector3 targetPosition = new Vector3 (rawPosition.x, 0.0f, 0.0f);
         GetComponent<Rigidbody2D>().MovePosition(targetPosition);
     }
 }

As you may see - the only thing I have done differently is used GetComponent to get a reference to the object's rigidbody, rather than just stating "RigibBody2D" as a reference itself. I hope this helps someone!