Australian laws should have no effect on a global forum. I don't see how they can enforce this in their country without resorting to widespread censorship of the internet. Gambling ads are everywhere. Maybe they will just ban gambling entirely, that way even if a user clicks on an ad or visits a casino site after watching a video ad the domain will be blocked by their ISP.
You should prepare yourself because most likely that is coming, social media websites already censor a great deal of content to keep their sites clean of opinions they do not like, however as much as those websites are popular among the population, they are not the whole internet, there are forums and blogs in which people are still able to express themselves freely, with this forum being a clear example of this, and governments will try to regulate the whole internet with similar laws all over the world.