function wptuts_youtube($atts, $content=null){

    extract(shortcode_atts( array('id' => ''), $atts));

    $return = $content;
    if($content)
        $return .= "<br /><br />";

     $return .= '<iframe width="560" height="349" src="http://www.youtube.com/embed/' . $id . '" frameborder="0" allowfullscreen></iframe>';

     return $return;
}
add_shortcode('youtube', 'wptuts_youtube');