How to center video tag in a div tag?

Question

I cannot seem to position this video tag with the usual "margin: 0px auto 0px auto;" Help lads! Thanks for looking into this!

#wrapper #trailer {
    position: absolute;
    z-index: 3;
    margin-top: 55px;
    width: 987px;
    height: 620px;
    background-color: #000;
    margin-right: auto;
    margin-bottom: 0px;
    margin-left: auto;
    border: 1px solid #009;
}
#wrapper #trailer #close {
    position: absolute;
    z-index: 2;
    top: 20px;
    right: 231px;
    cursor: pointer;
}
#wrapper #trailer video {
        margin-top: 0px;
    margin-right: auto;
    margin-bottom: 0px;
    margin-left: auto;
    border: 1px solid #009;
}

and html and explaining my scenario as requested :

<div id="trailer">
<img id="close" src="images/close.png" alt="close" />
<div id="video">
<video controls  autoplay="autoplay" poster="video/trailer.jpg" width="600"      onclick="if(/Android/.test(navigator.userAgent))this.play();">
<source src="video/trailer.mp4" type="video/mp4" />
<source src="video/trailer.webm" type="video/webm" />
<source src="video/trailer.ogv" type="video/ogg" />
<embed src="video/flashfox.swf" width="600" height="480"  flashVars="autoplay=true&amp;controls=true&amp;loop=true&amp;src=trailer.mp4" allowFullScreen="true" wmode="transparent" type="application/x-shockwave-flash" pluginspage="http://www.adobe.com/go/getflashplayer_en" />
</video>
</div>
</div>

Answer 1

Actually, html5 videos as well as images count as text when it comes to stylesheets. So, the only changes you would have to make would be in your css code. Using the <div id="video> tag you wrapped the video with, all you would have to add is:

#video {
   text-align: center;
   //rest of rules here
}

instead of playing with margins all day.

Answer 2

If you do not know your video's with you can still center it using css transforms:

video {
  position: relative;
  left: 50%;
  transform: translateX(-50%);
}