I have not watched the documentary yet. But does a snuff film HAVE to be commercial in order to be considered so? If not, well, there is now at least 1 known snuff film, released on the internet around the day this thread was made.
I have seen it, like quite a few people now, it's surprisingly easy to find. It is extremely disturbing at best, (Brad review voice) but the soundtrack was great.
Edit: Documentary answered my question.