When do episodes publish and why do they expire?
The time it takes for episodes to be made available on TVNZ is dependent on the online rights that we have for that show. For example, we can put most shows up immediately after they've finished airing on TV, and with premiering shows we can often put them up on TVNZ after they've aired on the US West Coast or when the episodes arrive at TVNZ.
With regards to rights, the period of time TVNZ can have a show and its episodes available in OnDemand can differ greatly from one show to the next. For example, we can have episodes of Shortland Street up for 6 months, while an Express show playing right after it airs in the U.S. may only be available for 14 days.
We sometimes have content with stacking rights too, where we're limited to how many episodes of a show we're allowed up at one time.
In saying the above, we're working really hard to change the length of time we get shows for, and how many episodes of a show we're allowed to have up at the same time. We're also working to get more full seasons of shows than ever before!