Reality film is a fairy new and modern genre of film. Reality film has come from reality TV series', more often than not they are one of the cheapest films to create as the actors are usually not professionally and all that is filmed is what actually occurs. Reality films were never really noticed as a specific genre up until 2002 when Jackass The Movie came out. Here is the trailer for Jackass, you can see that MTV also have a part in producing this film, this is because Jackass was a reality TV series on MTV before it was made into a film. This is the case with a lot of reality films.
You can see that Reality film genre is a new genre to the industry as on many websites that have information an genre it does not appear on the list. Therefore it is hard to find information on it. This website is an example of showing many genres apart from Reality. http://www.filmsite.org/filmgenres.html
Although it isn't written down we can have a good guess at what the features are of reality films contain some of these being :
Non-professional Actors/Actress'
Reality - True story line with real people
Feature Length
Comedy Value
Always to do with public interest at the time of creation