In the hidden footage you can see the family eating clay, especially the father. This comes from the mad artist in the show watched by the grandmother, who claims that clay is the medicine of a disease. That's also the reason for the father's obsession with Southafrica, as there is a whole culture eating clay for health.
There is a website for the surveillance company seen in the short film which has hidden on it hours more footage, in addition to images, emails and text logs from the family.
In an interview with Vice, Alan Resnick revealed this was originally shot as the pilot for a potential series. When the project wasn't greenlit, he and the team re-purposed the footage to work as a short film and accompanying ARG. In that same interview, he also stated that he'd be open to a continuing the project in the future, utilizing the original concept for a series.