I'm not sure that it's a bug in Opera that makes it open the current Web page instead of the Home page when clinking on the 'Playing Now' link.
The code (HTML and script) doesn't suggest a link to any page, except playing.php3, and the 'href' attribute is empty. So, it seems that browsers render an empty 'href' differently.
There's some info on script support in Opera...
http://www.opera.com/docs/specs/#ecmascript
Thomas