Get Multiple Embedded Youtube Videos to Play Automatically in Sequence

Using the Youtube IFrame API, you can do this easily.

The only part you need to configure here is the array of youtube IDs. You can retrieve those from the part after the /v/ in the URL (If need be, you can modify the javascript to load URLs instead of IDs. I just like this way better.

<div id="player"></div>
<script src="//www.youtube.com/iframe_api"></script>

<script>
    /**
     * Put your video IDs in this array
     */
    var videoIDs = [
        'OdT9z-JjtJk',
        'NlXTv5Ondgs'
    ];

    var player, currentVideoId = 0;

    function onYouTubeIframeAPIReady() {
        player = new YT.Player('player', {
            height: '350',
            width: '425',
            events: {
                'onReady': onPlayerReady,
                'onStateChange': onPlayerStateChange
            }
        });
    }

    function onPlayerReady(event) {
        event.target.loadVideoById(videoIDs[currentVideoId]);
    }

    function onPlayerStateChange(event) {
        if (event.data == YT.PlayerState.ENDED) {
            currentVideoId++;
            if (currentVideoId < videoIDs.length) {
                player.loadVideoById(videoIDs[currentVideoId]);
            }
        }
    }
</script>

Here is an example using the YouTube Iframe Player API.

There are two separate embeds (player1 and player2). The video autoplays when player1 has loaded, and it starts player2 when it completes.

Here is the jfiddle if you want to play around with it.

And the code:

<div id="player1"></div>
<div id="player2"></div>
<script>
    var tag = document.createElement('script');
    tag.src = "//www.youtube.com/iframe_api";
    var firstScriptTag = document.getElementsByTagName('script')[0];
    firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);

    var player1;
    var player2;

    function onYouTubeIframeAPIReady() {
        player1 = new YT.Player('player1', {
            height: '350',
            width: '425',
            videoId: 'OdT9z-JjtJk',
            events: {
                'onReady': onPlayerReady,
                    'onStateChange': onPlayerStateChange
            }
        });
        player2 = new YT.Player('player2', {
            height: '350',
            width: '425',
            videoId: 'NlXTv5Ondgs'
        });
    }

    function onPlayerReady(event) {
        event.target.playVideo();
    }

    function onPlayerStateChange(event) {
        if (event.data == YT.PlayerState.ENDED) {
            player2.playVideo();
        }
    }
</script>