Hi --- The site entry ad is set to only appear the first time you enter the site.  When you either wait for the ad to cycle through or click on the link above or below the ad a browser cookie is set  that allows you to bypass the ad in subsequent visits during your session.

More than 95% of all users do have their browser cookies set, however If a person doesn't have cookies set on their browser they won't be able to get through this ad and to the site until they do.