javascript gets nuked

I have a (existing before I installed YUI) block which contains javascript code (generated twitter.com badge). When I edit this block with YUI the javascript vanishes, and when I switch to text only mode it is gone.
Below is the code that causes the problem in the editor.

<div class="mytweets" style="margin: -10px;">
<script src="http://widgets.twimg.com/j/2/widget.js"></script>
<script>
new TWTR.Widget({
  version: 2,
  type: 'profile',
  rpp: 5,
  interval: 6000,
  width: 250,
  height: 300,
  theme: {
    shell: {
      background: '#7a2c2f',
      color: '#ffffff'
    },
    tweets: {
      background: '#9c3b3b',
      color: '#ffffff',
      links: '#4aed05'
    }
  },
  features: {
    scrollbar: false,
    loop: false,
    live: false,
    hashtags: true,
    timestamp: true,
    avatars: false,
    behavior: 'all'
  }
}).render().setUser('anonymous').start();
</script>


</div>