GlobalEventHandlers.onplay

element.onplay = handlerFunction;
var handlerFunction = element.onplay;

<p>This example demonstrates how to assign an "onplay" event to a video element.</p>

<video controls onplay="alertPlay()">
  <source src="mov_bbb.mp4" type="video/mp4">
  <source src="mov_bbb.ogg" type="video/ogg">
  Your browser does not support HTML5 video.
</video>

<p>Video courtesy of <a href="http://www.bigbuckbunny.org/" target="_blank">Big Buck Bunny</a>.</p>

<script>
function alertPlay() {
  alert("The video has started to play.");
}
</script>