If you watch the video, he explains it like this.
It relates to inheritance because something like 90% of boomers own their own home, which means theres millions of millennials who are expecting to inherit those homes
Primary residence is the house you live in, that isnt an investment property, and the primary residence has always been exempt to these kinds of taxes, and primary residence has never been part of the assets tests for Pensions.
So basically
1. He wants to start including PRIMARY RESIDENCE on Asset tests for Pensions, and to add a Property Tax to the PRIMARY residence (on-top of council rates)
2. Since old people dont have much liquid assets (House Rich, Cash Poor) - they will allow people to defer the unrealized until they're dead and the house is sold
3. The defered unrealised taxes are index to inflation - so the taxes owed will compound, so a massive amount of taxes will end up being owed to the government on death.
The end result is, no inheritance for millennials. They're annoyed that some millennials have inherited homes now haven't paid any taxes on it because they didn't sell their parents house after they inherited it, so they want to begin taxing unrealised gains on the primary residence to ensure the government gets the asset instead of the family