I never really got this mentality. I don't root for the home team just because they're my home team, and belittle their rivals just because they're from another state/country/city. If I take no interest in the sport I couldn't care less if they were National/Worlds/Olympic champion and born in my city. I've always felt a bit oddly out of place in certain social events because I'm not a hardcore fan of the home team or my alma mater's football team. It's the same thing with college football or the NFL. I work at a university and it's pretty awkward when I get asked about our team's recent games and I give a blank stare.
As for Akiko's YouTube video, personally I'm baffled by the response. The most I could make out of it is that Akiko has won enemies now that she's on top, but has not gotten enough fan support yet to counter it. Have you guys not realized that 700 out of 295K views is only 0.2% of the total views? Sure the ratio of thumbs up to down is very low, but that's because of the 295k only a few clicked the thumbs up rating. That to me suggests what I've already mentioned--not that there is substantial "hate" for Akiko from so-called "Yuna fans"--but that those nationalistic zealots have swarmed her YouTube video while a smaller fan base has left her more vulnerable.