Related Content with References in Drupal 7
I am sure you could do all of this in one view using a contextual filter and using that as a relationship to point to the movies in question, but, if you don't mind some php coding, you can do all of this pretty easily yourself and one simpler view.

1.  create a view that has a contextual filter using the actor reference field, eg,
it returns just the movies that contain that actor, and in fields, just nid of the 
movie node should be sufficient.  Make sure that this will reference any actor in the
movie, eg, all of the values of this field, not just the first one.


Then in your block hook, put in something along the lines of:

$node=menu_get_object();

$movies=array();
foreach ($node-&gt;NAME_OF_ACTOR_REFERENCE_FIELD as $actor) {
   $view=views_get_view('NAME_OF_VIEW_ABOVE');
   $view-&gt;set_arguments(array($actor['nid']));
   $view-&gt;execute();
   foreach ($view-&gt;result as $result) {
      $movies[$result-&gt;nid]=$result-&gt;nid;
   }
}


Assuming this is displayed on a page that is displaying a movie of course, what this does is grab the actors referenced in that node and then loops through them, grabbing each movie that has referenced them as well, and then stores that in an array.  Since we key this array to the movie's nid, we also create a unique list of movies.

So, now we have a list of movie nids so we can do something like:

foreach ($movies as $nid) {
  $node=node_load($nid);
  $content.='&lt;div class="movie-title-link"&gt;' . l($node-&gt;title, $node-&gt;path) . ' &lt;/div&gt;';
}


and return $content as the content of the block and style it however you want with css.

Caveat:  I am just learning D7 and a lot of times D6isms creep into play, and most of the above is just typed in from memory, so there may be subtle things you'll need to adjust (drupal_set_message() and print_r() are your friends) but this hopefully will help out.