UStream - Autoplay has no effect

The video allways autoplays, no matter what.

/**
 * the embedded flash displaying the ustream video
 */
function theme_emvideo_ustream_flash($embed, $width, $height, $autoplay, $options = array()) {
  static $counter;
  if ($embed) {
    $counter++;
    $autoplay = isset($options['autoplay']) ? $options['autoplay'] : $autoplay;
    $autoplay_value = $autoplay ? 'true' : 'false';

    $output .= "<object type='application/x-shockwave-flash' height='$height' width='$width' data='http://ustream.tv/flash/video/$embed' id='ustream-video-$counter' ><param name='movie' value='http://www.ustream.tv/flash/video/$embed' /><param name='allowScriptAccess' value='always' /><param name='quality' value='best' /><param name='scale' value='noScale' /><param name='wmode' value='transparent' /><param name='FlashVars' value='autoplay=$autoplay_value' /><param name='allowfullscreen' value='true' /></object>";
  }
  return $output;
}

Setting the autoplay to false here stops this.

<param name='FlashVars' value='autoplay=false' />