I just found this gem in WordPress forums, all props to **A.Morita**.

### [Is there a way to disable the new Media Manager?][1]

Summing up all the code published, this is it:

    /**
     * I WANT THE OLD UPLOADER BACK
     * All code by: A.Morita
     * URL: http://wordpress.org/support/topic/is-there-a-way-to-disable-the-new-media-manager/
     */

    /**
     * Old upload Thickbox
     */
    add_action( 'admin_head', 'remove_media_buttons' );
    
    function remove_media_buttons()
    {
        remove_action( 'media_buttons', 'media_buttons' );
        add_action( 'media_buttons', 'old_media_buttons' );
    }
    
    function old_media_buttons( $editor_id = 'content' ) 
    {
        $context = apply_filters( 'media_buttons_context', __('Upload/Insert %s') );
        
        $img = '<img src="' 
            . esc_url( admin_url( 'images/media-button.png?ver=20111005' ) ) 
            . '" width="15" height="15" />';
            
        echo '<a href="' 
            . esc_url( get_upload_iframe_src() ) 
            . '" class="thickbox add_media" id="' 
            . esc_attr( $editor_id ) 
            . '-add_media" title="' 
            . esc_attr__( 'Add Media' ) 
            . '" onclick="return false;">' 
            . sprintf( $context, $img ) 
            . '</a>';
    }
    
    /**
     * Featured image
     */
    add_action( 'wp_default_scripts', 'unset_media_views', 999, 1 );
    add_action( 'admin_head', 'remove_wp_print_media_templates' );
    
    function unset_media_views($scripts)
    {
        unset( $scripts->registered['media-views'] );
    }
        
    function remove_wp_print_media_templates()
    {
        remove_action( 'admin_footer', 'wp_print_media_templates' );
        remove_action( 'wp_footer', 'wp_print_media_templates' );
    }
    
    
    /**
     * Adjust Full Screen behavior
     */
    add_action( 'after_wp_tiny_mce', 'fullscreen_media_button' );

    function fullscreen_media_button()
    {
        ?>
        <script type="text/javascript">
        fullscreen.medialib = function() 
        {
            var href = jQuery('div#wp-content-media-buttons a.thickbox').attr('href') || '';
            tb_show('', href);
        }
        </script>
        <?php
    }

*[Wrapped as a plugin in Gist][2].*


  [1]: http://wordpress.org/support/topic/is-there-a-way-to-disable-the-new-media-manager/
  [2]: https://gist.github.com/4570587