Firstly i'd like to say that a few of the major people involved in the pro censorship debate such as Mary Whitehouse and James Ferman are dead now so that would be difficult to arrange an interview.
Also seeing as many of the nasties list were not prosecuted and eventually cleared, and just taking in to account many of the ridiculous titles targeted.
It would suggest much of the whole story was a knee jerk reaction to a few over exaggerated stories and grisly artwork.
The fact that most of the titles have now been legitimately released uncut in the U.K ,with no increase in power implement slaughter or rise of zombie outbreaks. Would also serve to deem anyone still aggressively wanting to argue the case to ban films like the ridiculous "Don't go in the woods" to look very foolish when being compared to reasoned arguments or critiques.
Perhaps feeling foolish some of the people concerned are not open to being included in a documentary on the subject, or would find it questionable and against their moral judgement.
Especially seeing a scenes from the films are shown throughout the documentary and trailers.
Maybe the film is anti censorship by necessity, any documentary about the phenomenon made in a pro censorship stance wouldn't present the clips or actually assess the films in a calm way, so would be biased as well.
By examining scenes and showing clips we can get a reasoned overview of the films in question, often the films are ridiculed or dismissed as shoddy productions by the critics in the trailer reel.
By the way the documentary and set covers all of the original 72 video nasties that the police seized and attempted to ban and prosecute.
The second set is about other films that were seized at the time but were never actually prosecuted or banned. This was called the section 3 list.
I feel the documentaries gives a good overview of how and why the Nasty situation originated, basically a lack of certification for home video.