If one wants to take photos up a woman's skirt, one should need her consent to do so. Doing so without her consent, IMO, is a violation of her privacy.
I'd argue that this is true in general, if you wish to make a person a subject of a video or photo.
However, I'm not sure that it should be illegal. And I've certainly "looked up" the skirts of various women, who were not attempting to be at all sexual, but who were kneeling or sitting - either to take care of a kid, or just to rest, or whatever. I always considered the right thing to do to be to look away. Not because I was wrong, but because I wasn't a perv.
And that was my point. We are discussing a guy who is apparently taking photos of women wearing short skirts, sitting down. He isn't sticking the camera in between their legs as they walk down the street, but at the same time, again, there's exactly one noteworthy step at the Lincoln Memorial, and it's where King was standing during his speech in the March on Washington. There's no real doubt that he is taking photos of women's crotches, but there's also no doubt that a person (male or female) in a short skirt, sitting with his/her legs wide open, is...on display.