video要素を一時停止する

videoElement.pause();

HTML

<video id="video" autoplay>
	<source src="media/sample.mp4">
	<source src="media/sample.ogv">
	<source src="media/sample.webm">
</video>

<p><button type="button" id="pause-btn">一時停止する</button></p>

JavaScript

var videoElem    = document.getElementById('video'),
    pauseBtnElem = document.getElementById('pause-btn');

pauseBtnElem.addEventListener('click', function() {
	videoElem.pause();
});