The purpose of this file is to allow a cosmetic change to the way you and your members view guests on the forum home page and on your "Who's Online" page to identify specific guests as being web crawlers/spiders. It in no way enables your web pages to be more easily indexed by web crawlers/spiders, you would use other methods to ensure easier indexing.
The file vBulletin Solutions provides you identifies only 11 spiders, and the aim of this service is to enable you to replace the default file with one that identifies more than 600 spiders.