The app itself may but being able to watch content on it over there is unlikely.
More info on Watching Optus Sport from overseas
Edit: It does not work on Christmas Island.
@Ray_YC hehehe, I believe Christmas Island is part of Australia territory, it is kinda like saying Tasmania is oversea.
It all depends if Optus recognise the IP address that you are connected from is an Australian IP address.
Haha I was waiting to be pulled up on that @SillyGogo , I know it is... over a sea/ocean