What happens when a video of "something" bad happens, a person is put in jail immediately for that "something", but the video is "banned"? And "something" is not even reported on... This is a great tool for stifling opposing politics of _any_ kind. And seems like the easiest way to start an oppressive tyranny than a method of stopping terrorist propaganda. Psychos don't need videos like this. Just watch movies, there…
Your argument requires beforehand authoritarian capture of all branches of the NZ government to make sense. At which point the whole suggestion is moot.