I can't say if watching pornography is moral or immoral.
What I know by experience is that no all pornography is worthy for all audiences, this is to say, if the watchers of those movies will appreciate what they see.
In my case, porno movies with lots of guys having sex with one young girl never caused me a single emotion, on the contrary I find those kind of movies bored as hell. On the other hand, my friends used to love them.
I was a teenager in my steps to be an adult and a French movie came to theaters, called Enmanuelle.
Those were years totally different than today. At the end of the 60s in San Francisco public parks was very common to see early in the morning young teenager girls walking around -some of them naked- after sleeping with hippies of all ages, and police used to say...nothing. Today such should be food for court cases against those men dreesed funny and without taking a bath for months.
The pornography movies of Emmanuelle included rape, but the movies were made in that way that the viewer -used to that kind of environment of the 70s- will enjoy them. My curiosity for pornography started with this kind of movies, and I watched all of them, because the producers made more than one of those movies.
Later, when the American porno style movies gained more popularity, I lost my appetite for pornography because those were full of quantity but almost no quality to my taste.
Was it immoral? Lets say yes, I was a teenager when I sterted to watch those movies at the movie theater.
Are those porno movies immoral? It depends.
To me, if sex in the film was made consensual and between a man and a woman, I do approve it.