Hey Rick,
regarding what you are doing at ~7:42 could you also use ths code:
[SerializeField] Camera caMainCamera;
Debug.Log(Input.mousePosition.x / Screen.width * caMainCamera.orthographicSize * 2 * caMainCamera.aspect);
Then you wouldn´t have to remember to change it if you change camera size, or could this bring other problems later on i am not aware of?