暂停 youtube 视频，youtube api

I'm trying to pause and play YouTube videos with the following code which is pretty much a copy from the Youtube API page:

// 2. This code loads the IFrame Player API code asynchronously.
var tag = document.createElement('script');
tag.src = "http://www.youtube.com/player_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 onYouTubePlayerAPIReady() {
    player = new YT.Player('player', {
        height: '315',
        width: '560',
        videoId: 'bpOR_HuHRNs',
    });
}

这是 jsFiddle 中的演示

但是，它不起作用.任何人都知道如何做到这一点?

function onYouTubePlayerAPIReady() {
    player = new YT.Player('player', {
        height: '315',
        width: '560',
        videoId: 'bpOR_HuHRNs',
    });
    document.getElementById('resume').onclick = function() {
        player.playVideo();
    };
    document.getElementById('pause').onclick = function() {
        player.pauseVideo();
    };
}