MyBook/Assets/script/BlackboardOne.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class BlackboardOne : MonoBehaviour
{
    public Button btnReturn;
    void Start()
    {
        btnReturn.onClick.AddListener(OnBtnReturnClick);
    
    }

    // Update is called once per frame
    void Update()
    {
        
    }

    private void OnBtnReturnClick()
    {
        GameManager.Instance.ImgMask.SetActive(false);
        GameManager.Instance.showVideoPlayer("d544ee389b313a457470fab9b220f981.mp4");
        this.gameObject.SetActive(false);
    }
}