Answer:
Scat films are made to appeal to people who are interested in coprophilia - a fetish for incorporating feces into sex play. They are WAY outside the mainstream!
Probably the most famous scat film right now is "2 Girls 1Cup", a trailer for a 2007 Brazilian scat film. The trailer features two women defecating into a cup, taking turns ostensibly eating the excrement, and puking it into each other's mouths. It became an internet meme shortly after it was posted along with videos showing people's reactions to viewing it - intentionally or because they were tricked into it. If the reactions displayed in the latter type of videos are any indication, you would be well advised to never view the film, lest you be scarred for life!