I really, really wish I knew the answer to this.
The first porn I saw blew my mind, and I'd love to see it again.
It was a vhs tape my friend had found belonging to his dad. There was a scene where a young 'prim-and-proper' english lady was being educated in Africa during the colonial era by an overweight elderly teacher, and she was getting horny and playing with herself under her clothes where he couldn't see.
Then a semi-naked young african warrior invades their house. He sees her, and she sees him, and they clearly like each other. He captures the elederly teacher in a net, so he cannot protect her, and proceeds to fuck her brains out, which she loves. The teacher watches voyeristically, in awe, through the net (i didn't get that bit at the time, but it has clear parallels to today's cuckold porn). The african warrior's dick was massive, as I recall, I'd never scene anything like it.
The scene was not very politically correct - but then would politically correct porn turn anyone on? I would love to know if anyone can identify this scene from description alone. I saw it about 15 years ago!