It's pretty much clear with sex, even using a condom. What is not clear is why there are two big TV sets on the wall practically right next to each other. And what's more, they are mounted at different angles! By the way, the man can clearly see how much he enjoys his girlfriend. Although to be honest she looks like a plank!
"Ran" is a bit of a mouthful. She was showing signs of attention to her stepson from the very first seconds of the video. Generally speaking, stepmothers are the easiest to divorce, they don't mind jumping on a younger guy's dick themselves, while living with his father (a richer man).