From as best I can tell this script should point you in the right direction. You'll have to assign camera 1 and camera 2 and the movie texture in the scene when you attach the script to something that has a collider set to be a trigger.
var camera1 : Camera;
var camera2 : Camera;
var movie : MovieTexture;
private var isPlaying : Boolean = false;
function OnTriggerEnter(other : Collider)
{
if(other.CompareTag("Player"))
{
camera1.enabled = false;
camera2.enabled = true;
StartMovie();
}
}
function StartMovie()
{
if(!movie.isPlaying)
{
movie.Play();
isPlaying = true;
}
}
function Update()
{
if(isPlaying && !movie.isPlaying)
{
camera1.enabled = true;
camera2.enabled = false;
isPlaying = false;
}
}