Looks like this might be in response to Telstra's unmetered Apple Music.
Streaming Music services: Spotify, Pandora, Google Play Music and IHeartRadio are now unmetered on Optus Post-paid plans (was previously only available on Prepaid)
Netflix and Presto are unmetered on the high end $100 and $120 plans, or a $10 addition to the $40/$65/$85 plans.
Can't seem to find anything official on the Optus website as yet. As per the other deal, may not be considered a true bargain, but could save you some money on data charges!
Edit: Offical FAQ from Optus site (thanks Goodfellha)
https://yescrowd.optus.com.au/t5/Blog/Postpaid-Music-and-Mob…
Now up on the Optus site:
http://www.optus.com.au/shop/promotions/stream
Does anybody know if the netflix unmetered would work over a hotspot direct to my WD Live? If thats the case.. I think i'd disconnect my ADSL as netflix is the only service where I use large amounts of Data.