The Greens are debating not committing to only Labour prior to the next election, and negotiating with both National and Labour if they hold the balance of power.
But don’t anyone think there is any real chance of a National-Green coalition. Most Greens are either communist background (Locke, Bradford, Norman) or hard-left. You possibly could do a deal just on environmental policy but you could never ever agree on economic policy, trade policy, defence policy etc etc,
As an example in the interview Sue Bradford demands National renounce and apologise for their previous actions. Yeah sure, right after Bradford apologises for the atrocities of the Chinese Communist Party.
So it is a smart move for the Greens, if they take it. But anyone who seriously thinks the Greens would vote in favour of a National Government is very mistaken.