Can I post this modification?
 

I did a nice mod based on a Joomla commercial hack. I am not sure f I can post it here so it is not perceived as an advertisement for the original developper as it requires purchasing the base javascript from his site.

This is the news slideshow seen here

Can a mod advise me on that please?

I don't see why not. There are other hacks released here which you need a comercial version to operate. One comes to mind with a Wiki of some sorts

From our Site Rules

16. Add-ons for commercial modifications may be released here providing a free version has been released here and:

1. It is fully functional
2. It is not time limited in any way
3. It is completely free to the user

17. Non commercial vBulletin modifications that integrate independent commercial software into vBulletin are permitted, providing the modification release thread is not created to promote sales of the commercial product. (Independent products are software that can be run without needing vBulletin.)