Limits vary in different regions of the country, most of the duckhunting scenes in the middle earth video were filmed in the lower South Island. In the central South Island (North Otago-Mid Canterbury) the limit is 50 birds per day. In the next region further south, Otago the limit is 25 birds and in the Southern-most region (Southland) the limit is 15 birds. All the filming took place in the first week of the Duck season, after which the hunting gets a little tougher.
I'm the guy in the video who gets a hard time for winning the calling contest and refuses to take his mask off