That's incorrect. When they advertise for teens, oftentimes they are teens under the age of 18. Also, the regular Joe or Josephine who is going to be clicking to watch it does not have an understanding that it would mean 18 or 19. That individual or individuals would have an understanding that it is a young girl.
The other point is, whether that woman or girl is over or under 18, in my experience, a number of women who have disclosed that they have been raped on video were not consenting either to the rape they endured or the posting of that rape publicly.