With this script, I'm using 'playerVars autoplay: 0' to prevent the video from autoplaying, but it seems to still be autoplaying.

PHP Code:
<script type="text/javascript">// <![CDATA[
/**
     * Put your video IDs in this array
     */
    
var videoIDs = [
        
'q_fso9SsG-g',
        
'Mv-MS8s3mMc'
    
];
    var 
playercurrentVideoId 0;
    function 
onYouTubeIframeAPIReady() {
        
player = new YT.Player('player', {
            
height'252',
            
width'300',
    
playerVars: { 'rel'0'autoplay'},
autoplay'0',
            
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>