Javascript InnerHTML - How to output not as plain text

Javascript InnerHTML - How to output not as plain text

I have install a joomla plugin by the name AllVideos Plugin. All I have to
do is to put some tags like this {youtube}h2TLC0zGwKE{/youtube} somewhere
in to my site and my video shows up!
In this point I need your help... In to my php code I have add a hidden
textbox that holds video's source and a div that will show video when I
click on an image using javascript.
Part of PHP code
<input id="video_url" name="video_url" type="hidden" value="" />
<div id="video"></div>
Part of JAVASCRIPT code
var Open = String.fromCharCode(123,121,111,117,116,117,98,101,125);
// {youtube}
var Close =
String.fromCharCode(123,47,121,111,117,116,117,98,101,125); // {/youtube}
var video = document.getElementById("video");
var video_url = document.getElementById("video_url");
...
video.innerHTML = Open+video_url.value+Close;
The problem is that youtube tags appear just as plain text! Take a look at
this image:
Any idea how I will make it work? Thank you in advance!