If you are fine with erotica, there is a website called literotica that he could go to that has plenty to pick from and is free. Of course there is everything, good and bad, but there are lots of categories that could help him figure out what he likes.
There are also numerous books, when I worked in a bookstore we had a huge section of erotica targeted at females, and another huge section of erotica targeted at males (with very little crossover as to who bought which), so I know there is plenty for him to pick from, even in specific genres or subcategories. And of course there are electronic books as well which he could read on an iPad if he doesn't have a book reader.
Since you're not limiting his porn consumption completely, only limiting his video porn, but okay with the written form, I think he'd have less reason to go behind your back. Males tend to be more visual, but if he can also get image porn (as in, pictures) he should be fine for now I guess.
I think often with these things it's pointless to try and ban them, but if you're merely trying to redirect it, it might be doable.