youtubeで映像を再生して5秒後にシェアボタン表示

youtubeにこんな便利なAPIがあったとは。
iframe 組み込みの YouTube Player API リファレンス
https://developers.google.com/youtube/iframe_api_reference?hl=ja#Playback_status

下記のような機能（関数）を使いました。

動画の再生を開始してからの経過時間を秒数で返します。
player.getCurrentTime():Number

<!-- 1. The <iframe> (and video player) will replace this <div> tag. -->
<div id="player"></div>

<script>
	// 2. This code loads the IFrame Player API code asynchronously.
	var tag = document.createElement('script');

	tag.src = "https://www.youtube.com/iframe_api";
	var firstScriptTag = document.getElementsByTagName('script')[0];
	firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);

	// 3. This function creates an <iframe> (and YouTube player)
	//    after the API code downloads.
	var player;
	function onYouTubeIframeAPIReady() {
		player = new YT.Player('player', {
		height: '390',
		width: '640',
		videoId: '-PdPCGkaOyM',
		events: {
			'onReady': onPlayerReady,
			'onStateChange': onPlayerStateChange
			}
		});
	}

	// 4. The API will call this function when the video player is ready.
		function onPlayerReady(event) {
		event.target.pauseVideo();
	}

	// 5. The API calls this function when the player's state changes.
	//    The function indicates that when playing a video (state=1),
	//    the player should play for six seconds and then stop.
	var done = false;
	function onPlayerStateChange(event) {
		setTimeout(showTime, 5000);
		function showTime() {
			if (!done) {
				if(5 < player.getCurrentTime()){
					showGood();
					done = true;
				}else{
					setTimeout(showTime, 1000);
				}
			}
		}
	}
	function showGood() {
		$('#shareBox').fadeIn(500);
	}
</script>

<div id="shareBox">
	<!--シェアボタンを入れておきましょう-->
</div>