Hello and welcome.
I also loaded the website in two different versions of Safari. The only ads I see are in the lower right, under the Other Sites section. As Spawn_Dooley mentioned, AdBlock may help you out, as we are not seeing the issue. It could also be that you have some form of adware on your Mac. You could try downloading, installing, and running:
AdwareMedic
-Have any of your forum members reported the ad issue to you?
-Does it happen in other browsers such as Google Chrome or Firefox?
-Have you tried it on any other computers you have access to?
C