Scriptalicious script - "Preview" feature hangs in FireFox

Try this... using firefox (3.6 is what I'm using)...

Go to the demo page: http://ckeditor.com/demo
Click the "New" icon to get an empty editor.
Click the "Source" icon to go into "source" mode.

Paste this code:
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/prototype/1.6.0.3/prototype.js"></script>

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/scriptaculous/1.8.1/scriptaculous.js"></script>

Then click the "Preview" icon... It opens a new window which never finishes loading (For me at least, on 2 different computers with firefox). Interesting thing is, it loads fine in IE and Chrome...

Any ideas?