Trouble With Loading Bar Script C# Unity 5

I was following this tutorial on how to make a loading screen on YouTube. I have followed his script exactly but I am getting all sorts of errors and I can't figure out why. YouTube Tutorial

 using UnityEngine;
 using System.Collections;
 
 public class LoadingScreen : MonoBehaviour {
 
     public string levelToLoad;
 
     public GameObject background;
     public GameObject progressBar;
     public GameObject text;
 
     private int loadProgress = 0;
 
     // Use this for initialization
     void Start () {
         background.SetActive (false);
         progressBar.SetActive (false);
         text.SetActive (false);
     }
 
     public void GoMusicPlayer02(){
         StartCoroutine(DisplayLoadingScreen(levelToLoad));
     }
     
     // Update is called once per frame
     void Update () {
         IEnumerator DisplayLoadingScreen(string level){
             background.SetActive (true);
             progressBar.SetActive (true);
             text.SetActive (true);
             
             progressBar.transform.localScale = new Vector3(loadProgress, progressBar.transform.localScale.y, progressBar.transform.z);
             
             text.GetComponent<GUIText>().text = "Loading Progress " + loadProgress + "%";
             
             AsyncOperation async = Application.LoadLevelAsync(level);
             while(!async.isDone){
                 loadProgress = (int)(async.progress * 100);
                 text.GetComponent<GUIText>().text = "Loading Progress " + loadProgress + "%";
                 progressBar.transform.localScale = new Vector3(async.progress, progressBar.transform.localScale.y, progressBar.transform.z);
                 
                 yield return null;
             }
         }
     }
 }