When you travel by air with film or video equipment there are restrictions on dangerous goods including the lithium batteries that you will almost certainly be taking with you.
The most well-known restriction on lithium batteries is that you must not put loose or spare batteries in checked-in baggage.
Here is the official Air New Zealand policy about travelling with lithium batteries updated for 2017. It has a handy table to help you decide what is acceptable. It can be helpful to carry a printed copy with you in case you encounter check–in staff are not fully up to speed.
Air New Zealand, like many airlines, also has a guide on their website. This website guide also warns that your batteries should have the original manufacturers labels on them that show capacity or lithium content.
More detailed documentation from airlines sometimes refers to a requirement that batteries and cells must be of a 'type proven to meet the requirements of the UN manual of tests and criteria'. Reputable manufacturers have certificates showing that their batteries meet this criteria. They can usually be found by a Google search for '[Insert manufacturer] batteries proven to meet the requirements of the UN manual of tests and criteria'
It's important that we all comply with these restrictions, they may seem like a nuisance but they are there to keep us all safe.
IATA document Lithium Battery Guidance Document Revised 9 March 2016
Lithium batteries for film Crews 2017.pdf