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.
I’m sure they would just follow Canada’s lead and start censoring websites from their citizens. It’s pretty crazy that this is happening to be honest but at least people still have the option to use VPNs for now. I’m sure someday in the not too distant future these countries will start making VPN use illegal.