Mmmm AdFly, hate it, you are normally able to skip it after 5 seconds in the top right corner. If this is the exact site you are getting and you are unable to click skip I suggest PMing the owner of the map and/or markings to see if they are able to send you a direct link.
AdFly is added by the forums, I think it helps pay for the forum or game (don't quote me on that though). It is a breeding ground for viruses so try not to dig into it