"Joomla extensions and Joomla templates by JoomlaShine.com"
To remove those hidden ads, just open the file data.php and comment the line
echo 'Joomla extensions and Joomla templates by JoomlaShine.com';
Overall, it's a good extension.
Let me explain about the link here.
1. This link is not truly a hidden (!) link. When you do right-click on the slideshow you will see that link too, so it’s visible for users.
2. Before downloading the product you are informed clearly about the link and you must agree to the term in order to download the product.