What this extension does?
It blocks a user to reach a page directly if it is to be reached through other page.
Example: Suppose you have a file give away and for that the user has to fill a form and after submitting he is forwarded to the file download page. Now if the download page URL is circulated, many will get the download without filling the details as they have by-passed the system set by you.
The role of this extension is, moment the file download page link is tried to open directly, it will show a blank page with a system message asking the user to first goto the required page and when OK is clicked, he is automatically directed to the page set up by you.
I find this small extension very useful.