Version: 2017.4
public float duration ;

Description

The time, in seconds, that the movie takes to play back completely.

Note that duration is only available once the movie has started. Until then duration will return -1. If you need to know the duration of a movie before it is played, consider extracting this information offline and creating a text asset. You can then look up the duration given the movie name.

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour { public MovieTexture mov; public GUIText gui; void Start() { gui.text = mov.duration.ToString(); } }