[asdfadrian]

In your bbcode manager for the replace code you want to do something like this if you want the user viewing the thread to have a post count greater than 50.

PHP Code:

<if condition="$bbuserinfo[posts] > 50">
You can view this hidden message!
</else>
You must reach 50 post counts in order to view this content.
</if> 


Note: The variable $userbbinfo is for vbulletin templates, if you are using a custom made page, you will need to include the globals.php, or define your variables if you have your own variable system.

I hope this helps!