plugins.click_to_play でブロックした YouTube の埋め込み動画にサムネイルをつける

_readme.txt

clicktoplay.xml を chrome フォルダに保存。
Stylish で使う場合はフルパスに直すこと。

clicktoplay.xml

<?xml version="1.0"?>
<bindings id="aiueo"
          xmlns="http://www.mozilla.org/xbl"
          xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
          xmlns:html="http://www.w3.org/1999/xhtml"
          xmlns:xbl="http://www.mozilla.org/xbl">

<binding id="c2p_youtube">
	<implementation>
		<constructor><![CDATA[
			var embed = this.parentNode;
			var vid = embed.src.match(/\b[\w-]{11}\b/);
			if (vid && vid[0]) {
				embed.style.backgroundImage = "url(\"http://img.youtube.com/vi/" + vid[0] + "/mqdefault.jpg\")";
				embed.style.backgroundPosition = "center center";
				embed.style.backgroundRepeat = "no-repeat";
				embed.style.backgroundSize = "cover";
				embed.style.borderRadius = "12px";
			}
		]]></constructor>
	</implementation>
</binding>

<binding id="c2p_youtube_iframe">
	<implementation>
		<constructor><![CDATA[
			var embed = this.parentNode;
			var vid = document.documentURI.match(/\b[\w-]{11}\b/);
			if (vid && vid[0]) {
				this.parentNode.style.backgroundImage = "url(\"http://img.youtube.com/vi/" + vid[0] + "/mqdefault.jpg\")";
				embed.style.backgroundPosition = "center center";
				embed.style.backgroundRepeat = "no-repeat";
				embed.style.backgroundSize = "cover";
				embed.style.borderRadius = "12px";
			}
		]]></constructor>
	</implementation>
</binding>

</bindings>

userContent.css

@charset "utf-8";
@namespace url(http://www.w3.org/1999/xhtml);

embed[src*="youtube.com/v/"]:-moz-handler-clicktoplay > div {
  -moz-binding: url("clicktoplay.xml#c2p_youtube") !important;
}

embed[src*="youtube.com/v/"]:-moz-handler-clicktoplay > *|vbox {
  background-image: none !important;
}
@-moz-document url-prefix("http://www.youtube.com/embed/") {

  embed:-moz-handler-clicktoplay > div {
    -moz-binding: url("clicktoplay.xml#c2p_youtube_iframe") !important;
  }
  embed:-moz-handler-clicktoplay > *|vbox {
    background-image: none !important;
  }

}