At least here, AN gets a lot of material from 
Korean fansub sources - so sometimes have shows 2 
weeks after aired in Japan - so these fansubs 
have not been acquired.  As long as the shows 
have not been commercially bought and released I 
personally think they are okay to show at 
conventions.  Cons are not selling these shows, 
they are showing 1 episode for review and/or 
entertainment purposes - and at least our local 
con allowed anyone to watch - con attendee or not 
so no one paid for the priviledge to view.  If a 
person watching likes the show, they are much 
more likely to buy the commercial release if/when 
made available and also to buy goods for the show.