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<?php
/**
 * Plugin Name: Deactivate oEmbed
 * Description: Deactivate oEmbed in WordPress 3.5 and earlier
 * Version:     0.0.1
 * Author:      Frank Bültge
 * Author URI:  http://bueltge.de/
 */

remove_filter( 'the_content', array( $GLOBALS['wp_embed'], 'autoembed' ), 8 );