It's worth watching the short video, they specifically address it - link with timestamp:
Where I live, (Northeastern US) there are art fairs all over the place during the summer. They travel from park to park, every weekend showing up in a different place; and they look just like what's in the video. (Except they don't have the requirement that everything has to have something to do with the internet.)
So, you could define it an "internet art fair" and everyone would know exactly what you're talking about.
"Internet Flea Market" sounds pretty great actually! :-)
Cheers