[toivo]

where do you find the url requested below;
"// cron url from <img src=
$cron_url = 'http://example.com/testvb/cron.php?' "

example.com is the URL of your site, testvb is the name of the folder where your forum is.

- I added a new cron under AdminCP -> scheduled tasks pointing to this run_cron.php file.

The script cannot be run under vBulletin Scheduled Tasks. The purpose of the forum_read.php file is to read the home page of the forum once every 5 minutes so that the Scheduled Tasks are triggered to run even during low forum activity. The Scheduled Tasks in vBulletin are run only if the forum is accessed, and getting a cron (the cron in the operating system) job to run forum_read.php once every 5 minutes to access the forum guarantees that the Scheduled Tasks are run regularly, independent of the forum activity.

You may have to tweak the forum_read.php script to run it on the same server, I run it from a different server.

- Also does the EI mod, only run when someone actually opens the forum

That is true. The script forum_read.php makes sure that the forum is accessed every 5 minutes, independent of the actual user activity.