When it comes to pornography the term 'Gonzo' refers to a style of film making pioneered in the 1990s by directors such as Seymore Butts and Ben Dover.
Gonzo porn took the storyline out of adult movies and headed straight for the sex. No longer would the pornoholic have to fast forward through 10 minutes of inept dialog to get 5 minutes of sex. They got sex throughout the whole video.
Gonzo porn was not always shot in the first person or in point-of-view fashion as some have suggested here and the quality of the movie depended largely on who was producing it.
Half the adult videos you can rent fall into the Gonzo genre.