Firefoxでプラグインブロック時にブロックしたコンテンツ名を表示。Firefox 22以降はデフォルトで追加されたので意味なし。

Firefox click-to-play display plugins name.css

embed,
object{
  text-align: center !important;
}

embed:after,
object:after{
  /*height: 20px !important;*/
  color: #ffffff !important;
  position: relative;
  font-size: 14px !important;
  font-family: sans-serif !important;
  top: -20px !important;
  text-shadow: 1px 1px 2px #000000, -1px -1px 2px #000000 !important;
}

embed[type="application/x-shockwave-flash"]:after,
object[type="application/x-shockwave-flash"]:after{
  content: 'Adobe Flash Player' !important;
}

embed[type="video/mp4"]:after,
object[type="video/mp4"]:after{
  content: 'mp4 video file' !important;
}

embed[type="application/x-mplayer2"]:after,
object[type="application/x-mplayer2"]:after{
  content: 'Windows Media Player' !important;
}

embed[type="application/x-silverlight-2"]:after,
object[type="application/x-silverlight-2"]:after{
  content: 'Microsoft Silverlight' !important;
}

embed[type="application/pdf"]:after,
object[type="application/pdf"]:after{
  content: 'PDF' !important;
}