Shia Luck wrote...
TL;DR It is possible for her to develop that accent and fluency within a year and a half. Exceptional? Yes. Impossible? No.
Have fun 
I agree, accent and fluency can be learned in as little as a year, but only if you actually spend time with native speakers, immerse yourself in the language and culture, and really work hard on an accent/language improvement course. The video I saw was from 2011, so she had like 1.5 - 2 years to do this. Now, some people are probably completely exceptional and can learn all this by doing nothing but spending time with ESL courses, watching american media and reading english internet discourse..
However, the evidence is scant on whether she's actually spent this amount of time in the U.S. or if she's really a polyglot/linguistic geek/savant. Google's not giving me enough info on her whereabouts or activities, and her Facebook page is nothing but photos of her in auto shows and cosplaying events.
I personally have nothing against the OP, or anyone else here, and I think the platinum duo was great. Just my 2c.