THis is actually very old news to anyone who was in the voyeur niche back in the early days. Upskirt was floating around the net way before the webcam explosion, or "hidden video" in hotel rooms, etc. It was usually acquired by some guy with a video cam stuffed in a duffle bag, with the zipper open just enough for the lens to peek out, and they would walk around shopping malls, etc., putting the bag down next to a girl in a skirt to get the "money" shot. Some used wireless pinhole cameras on their shoes, that transmitted the signal to the parking lot, where they had a VCR set up on battery.
There used to be a whole underground dedicated to this stuff, and the guys doing it often times didn't even ask for cash, but rather traded with others for new content. But I think most of the guys eventually got caught or arrested.