YouTube Playlist Embed Script for Multiple Playlists on a Single Page (jQuery/CSS/HTML + CodePen)

You're using the same id for multiple div. You can only specify a unique id. You can use class instead of id for ytpl-thumbs and use unique id for each players :

Check this fiddle

HTML

<div class="sidebar">
  <h1>Playlist (1): Birds</h1>
  <div class="container">
    <div class="ypt_wrapper">
      <div class="video embed-container">
        <div id="ytpl-player1" data-pl="PLBhKKjnUR0XB8DwQwXqBsChb48E8jzfr-">
        </div>
      </div>
      <div>
        <h2 class="ytpl-title"></h2>
        <div class="ytpl-desc"></div>
      </div>
      <div class="ytpl-flexslider">
        <ul class="ytpl--thumbs slides"></ul>
      </div>
    </div>
  </div>
</div>

<div class="sidebar">
  <h1>Playlist (2): Owls</h1>
  <div class="container">
    <div class="ypt_wrapper">
      <div class="video embed-container">
        <div id="ytpl-player2" data-pl="PLBhKKjnUR0XAM2Wvi7JY5gLRpFLzIE-An">
        </div>
      </div>
      <div>
        <h2 class="ytpl-title"></h2>
        <div class="ytpl-desc"></div>
      </div>
      <div class="ytpl-flexslider">
        <ul class="ytpl--thumbs slides"></ul>
      </div>
    </div>
  </div>
</div>

<div class="sidebar">
  <h1>Playlist (3): Misc. Animals</h1>
  <div class="container">
    <div class="ypt_wrapper">
      <div class="video embed-container">
        <div id="ytpl-player3" data-pl="PLBhKKjnUR0XCGuLxsESq7WMlIwZIH9tIi">
        </div>
      </div>
      <div>
        <h2 class="ytpl-title"></h2>
        <div class="ytpl-desc"></div>
      </div>
      <div class="ytpl-flexslider">
        <ul class="ytpl--thumbs slides"></ul>
      </div>
    </div>
  </div>
</div>

Javascript

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

var players = new Array();
var players_list = ["ytpl-player1", "ytpl-player2", "ytpl-player3"];

var nowPlaying = "ytpl-playing";
var nowPlayingClass = "." + nowPlaying;

function getPlaylistData(playerName) {
    var apiKey = 'AIzaSyDI4rWo_wVAxRZEIgF6_8sRZDj8OCOZZ38';
    var url = 'https://www.googleapis.com/youtube/v3/playlistItems?part=snippet';
    var data = {
        'playlistId': $('#' + playerName).data('pl'),
        'key': apiKey,
        'maxResults': 4
    };

    $.get(url, data, function(e) {
        buildHTML(playerName, e.items)
    })
}

function buildHTML(playerName, data) {
    var list_data = '';
    data.forEach(function(e, i) {
        var item = e.snippet;
        if (item.thumbnails) {
            list_data += '<li><button data-ytpl-index="' + i + '" data-ytpl-title="' + item.title + '" data-ytpl-desc="' + item.description + '"><p>' + item.title + '</p><img alt="' + item.title + '" src="' + item.thumbnails.medium.url + '"/></button></li>';
        }
    });
    $('#' + playerName).closest('.ypt_wrapper').find('.ytpl--thumbs').html(list_data);
}

// generate playlist items once main player has loaded
function onPlayerReady(event) {
    getPlaylistData(event.target.name);
}

function onYouTubeIframeAPIReady() {
    for (item in players_list) {
        players[players_list[item]] = new YT.Player(players_list[item], {
            height: '360',
            width: '640',
            playerVars: {
                listType: 'playlist',
                list: $('#' + players_list[item]).data('pl')
            },
            events: {
                'onReady': onPlayerReady,
                'onStateChange': onPlayerStateChange
            }
        });
        players[players_list[item]].name = players_list[item];
    }
}

function updateTitles($this) {
    $('#ytpl-title').text($this.data('ytpl-title'))
    $('#ytpl-desc').text($this.data('ytpl-desc'))
}

function onPlayerStateChange(event) {
    var $buttons = $('#' + event.target.name).closest('.ypt_wrapper').find('.ytpl--thumbs').find('button');

    var currentIndex = event.target.getPlaylistIndex();

    // remove existing active class, add to currently playing
    if (event.data === YT.PlayerState.PLAYING) {
        $buttons.removeClass(nowPlaying);
        $buttons.eq(currentIndex).addClass(nowPlaying);
    }

    // if last video has finished playing
    if (event.data === YT.PlayerState.ENDED && currentIndex === $buttons.length - 1) {
        $buttons.removeClass(nowPlaying);
    }
    updateTitles($buttons.eq(currentIndex))
}

// handle playlist button click
$(document).on('click', '[data-ytpl-index]:not(".ytpl-playing")', function(e) {
    e.preventDefault();
    var $this = $(this);
    var index = $this.data('ytpl-index');
    var playerName = $(this).closest('.ypt_wrapper').find('iframe').attr('id');
    updateTitles($this);

    if (navigator.userAgent.match(/(iPad|iPhone|iPod)/g)) {
        players[playerName].cuePlaylist({
            listType: 'playlist',
            list: $('#' + players_list[playerName]).data('pl'),
            index: index,
            suggestedQuality: 'hd720'
        });
    } else {
        players[playerName].playVideoAt(index); //Play the new video, does not work for IOS 7
    }
});