How do Skyrim's townsfolk react to seeing a player walk around in suggestive body mods? They don't. They just repeat the same lines they'd say normally, but that's exactly what makes this video funny.
Shinji72 decided to "recreate" a video you may have seen floating around recently, where a woman walks around New York for ten hours while documenting some of the street harassment she experienced. It's worth noting that, unlike this Skyrim parody, the original video made a point of dressing the woman in normal, everyday clothes—but she was still harassed left and right.
While I'm not sure about Shinji72's intent with the Skyrim video—it would be easy to read it as something that downplays how awful the real-life harassment video is, since it's sort of making fun of it—I do think the result is fascinating. Obviously, the NPCs would react in the exact same way were this a male character. Still, the context here means we read some of what the NPCs say a little differently. Lines like "you should see me when you get bored, stranger" come off as catcalls in this context, even if that's not actually what they are. I don't note this to, like, demonize the game or anything, though I do think it highlights how weird it is that people in games are programmed to react to you whenever you walk by.
Finally, whatever mod was used in this video? That's definitely not how boobs work. Unless you're trying to recreate Ryse breasts, that is.