Do you not already know the duration of the movie clip from what you see in the import settings as well as in your finder? You also know what framerate it plays so you could just create a yield for that duration.

Start a timer and know the time for example

void Awake() {

startTime = Time.time;

}

if(movieTexture.isPlaying == true) {

elpasedTime = Time.time-startTime;

}

Now, elapsedTime will return your movieTexture Duration

We don't have a in built method to read the time but there's a traditional way..

function Awake() {

startTime = Time.time;

}

Now some where in update or OnGUI write this following code..

if(movieTexture.isPlaying == true) {

elapsedTime = Time.time - startTime;

}

Now elapsedTime returns the time taken by the movieTexture