If you want to play video automatically when visitor scroll the youtube video section on any page then given below code can help you.
Given below script will automatically play the video when visitor will scroll the youtube video section and it will automatically pause when visitor will scroll to other content section on the page.
Add given below javascript into footer of the page.
<script type="text/javascript">
//play when video is visible
var videos = document.getElementsByTagName("iframe"), fraction = 0.8;
function checkScroll() {
for(var i = 0; i < videos.length; i++) {
var video = videos[i];
//console.log(video);
var x = 0,
y = 0,
w = video.width,
h = video.height,
r, //right
b, //bottom
visibleX, visibleY, visible,
parent;
parent = video;
while (parent && parent !== document.body) {
x += parent.offsetLeft;
y += parent.offsetTop;
parent = parent.offsetParent;
}
r = x + parseInt(w);
b = y + parseInt(h);
visibleX = Math.max(0, Math.min(w, window.pageXOffset + window.innerWidth - x, r - window.pageXOffset));
visibleY = Math.max(0, Math.min(h, window.pageYOffset + window.innerHeight - y, b - window.pageYOffset));
visible = visibleX * visibleY / (w * h);
if (visible > fraction) {
playVideo();
} else {
pauseVideo();
}
}
};
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', {
events: {
'onReady': onPlayerReady,
'onStateChange': onPlayerStateChange
}
});
};
// 4. The API will call this function when the video player is ready.
function onPlayerReady(event) {
window.addEventListener('scroll', checkScroll, false);
window.addEventListener('resize', checkScroll, false);
//check at least once so you don't have to wait for scrolling for the video to start
window.addEventListener('load', checkScroll, false);
};
function onPlayerStateChange(event) {
if (event.data == YT.PlayerState.PLAYING) {
//console.log("event played");
} else {
//console.log("event paused");
}
};
function stopVideo() {
player.stopVideo();
};
function playVideo() {
player.playVideo();
};
function pauseVideo() {
player.pauseVideo();
};
</script>
And add the iframe embed code on your page
<iframe id="player" type="text/html" width="640" height="390" src="http://www.youtube.com/embed/QUnxtCe95Ww?enablejsapi=1&autoplay=1" frameborder="0"></iframe>
All the best!!