Igebotz being the first to post on this thread already explained the dot same way I understand it's meaning, for the admin, it's easy to understand why he has five red dots under his username, he is the only person on this forum with that badge, and with the admin username, it should be very easy for anyone to understand that he is the admin of this forum, just incase anyone imposter tried to impersonate him.
And for the yellow dots, that simply means the user is a moderator in their respective local board.
But something I do not understand at the moment is if the yellow dot is generalized for all moderators, both local and international, or is it just specific or limited to local board moderators alone?.