Auto populate a meta box field from another meta box field when publish or save

/* Do something with the data entered */
add_action( 'save_post', 'myplugin_save_postdata' );

/* When the post is saved, saves our custom data */
function myplugin_save_postdata( $post_id ) {

  // First we need to check if the current user is authorised to do this action. 
  if ( 'page' == $_POST['post_type'] ) {// checks for post type.
    if ( ! current_user_can( 'edit_page', $post_id ) )
        return;
  } else {
    if ( ! current_user_can( 'edit_post', $post_id ) )
        return;
  }

  $mydata = get_post_meta($post_id,'speaker',true);

  update_post_meta( $post_id, '_your_meta_key', $mydata ); // replace your _your_meta_key with Episode Titles key

}

This might be what you need. The current code works for pages only, but can be modified to work with posts or CPTs aswell.

What this does is, it grabs the data from your speaker field and updates that value into your episode title. Be sure to add the correct key for your Episode Titles