VJ means whatever you want it to mean, I guess. At some of the vidding cons I go to, VJ is just the term for a person who designs a vidshow, coming up with what vids to show and in what order. It's at least potentially separate from the technical implementation of how the vids are shown. In this case, at Vidukon they're using their custom Conline software (conline.club) which allows synched watching of video from youtube or vimeo, so all a VJ does is go into conline and enter some metadata and the streaming link for each video and the software does the rest.