Changes Page HTML?

After turning on your module, any page with the [video:URL] tag breaks. As soon as I turn off your module the page works just fine again. When the module is turned off the code on an average page looks like this:

<div id="page-wrapper">
   <div id="content">
      <div class="column1-default">
         <div id="node-194" class="node">
            <div class="content">
               <p>Here is an interesting video for you to review.</p>
               <p>[video:http://www.youtube.com/watch?v=w9BfLMHNhxE]</p>
            </div>
         </div>
      </div>
      <div class="column2-default">
          .... more content here ....
      </div>
   </div>
</div>

So far looks good. However when I turn on the module, I now get this:

<div id="page-wrapper">
   <div id="content">
      <div class="column1-default">
         <div id="node-194" class="node">
            <div class="content">
               <p>Here is an interesting video for you to review.</p>
               <p><object width="400" height="334" data="http://www.youtube.com/v/w9BfLMHNhxE&autoplay=1" type="application/x-shockwave-flash"/></p>
            </div>
         </div>
      </div>
   </div>
</div>
<param value="http://www.youtube.com/v/w9BfLMHNhxE&autoplay=1" name="movie"/>
<param value="transparent" name="wmode"/>
...... remainder of column1 content ......
<div class="column2-default">
   .... more content here ....
</div>

Somehow the module has closed off all the open DIVs in column 1, stuck the param's at the end, then pasted all the remaining page content after it. How could this have happened? I'm a bit confused why it doesn't work. Your video_filter_flash function looks straightforward in creating as output the entire string including the param's. What could have caused it to be reconfigured this way?

I'm running Drupal 5.7, PHP 5.2.3, Apache 2.2.8, MySQL 5.0.45. I previously had embedfilter installed but it is broken for YouTube, and I had tried the new jQuery Media but it is more than what our users need. Both have now been uninstalled.