Ok, I got it.
When you call
www.videovbox.co.uk/register, you get a 404 error page directly from IIS (your web server):
HTTP/1.1 404 Not Found
Content-Length: 1635
Content-Type: text/html
Server: Microsoft-IIS/6.0
X-Powered-By: ASP.NET
Date: Wed, 14 Oct 2009 08:04:52 GMT
...
HTTP Error 404 - File or directory not found.
Internet Information Services (IIS)
...
In this state it's impossible for ReDJ to manage redirections, because request doesn't come to Joomla at all.
The solution is to add an ErrorDocument option in .htaccess file, as indicated in item edit's page. Usually is:
This works with Apache web server. It should work also with IIS.
Let me know,
Luigi