What is most striking is how open and public the man is about what he is doing. It doesn't seem at all credible that no one -- discounting, of course, the person filming -- noticed.
An article in the Korea Times recently looked at the topic of sex crime on the subway, and many women here, rightly or wrongly, seem to think that Seoul is a dangerous place at night.
One Korean phenomenon that stands out aside from subway gropers are the flashers. Many girls -- certainly a very sizeable minority at least -- I have spoken to here have seen one, mostly during their high school years. Known as "Burberry men" because of their penchant for Burberry trench coats, they hang around outside high schools and flash students at first opportunity. So common they seem to be that The Wonder Girls, a Korean girl group, featured one having his ass kicked in one of their music videos (skip to 1:30 if you can't stomach K-pop).
There are perverts and strange folk of every description in all countries. But, for whatever reason, some of the harassment that goes on here seems to have a uniquely Korean, or at least Asian, dimension. Culture manifests itself in sometimes strange and insidious ways. Japan has women-only subway carriages, whereas the U.S., Britain and Ireland do not for a reason.
Just why that is, and why Burberry men aren't known about Dublin isn't easy a question to answer, nor am I sure it is one which can be answered definitively.
Either way, it's for another day.