phantom parameter in function
<p>Going through some examples on building a video control panel for an HTML5  element and a a pattern I don't understand popped up here?</p>

<p><a href="http://dev.opera.com/articles/view/introduction-html5-video/#scripting" rel="nofollow">http://dev.opera.com/articles/view/introduction-html5-video/#scripting</a></p>

<p>in particular:</p>

<pre><code>var v = document.getElementById('videoPlayer');
v.addEventListener('timeupdate',updateTimeDisplay,true);

function updateTimeDisplay(e) {
  document.getElementById('timeDisplay').innerHTML = e.target.currentTime;
}
</code></pre>

<p>Where did that 'e' come from in the function? What does it reference? Where can I learn more about what it is doing?</p>
