After rewatching the video, I realized that line 19, which handles transforms (`transform.position = transform.position + (Vector3.left * moveSpeed) * Time.deltaTime;`), was missing in the script provided in the link under "Scripts."
Also the if condition in written Script is mentioned as ">" that is mismatched in the video that is "<". So the correct script that would make the game properly run would be:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PipeMoveScript : MonoBehaviour
{
    public float moveSpeed = 5;
    public float deadZone = -45;

    // Start is called before the first frame update
    void Start()
    {

    }

    // Update is called once per frame
    void Update()
    {
        transform.position = transform.position + (Vector3.left * moveSpeed) * Time.deltaTime;
        if (transform.position.x < deadZone)
        {
            Destroy(gameObject);
        }
    }
}