This isn't a problem with just Arthur, almost all animated series are aired overseas before they are in the U.S., of which I never understood why that is, but it is. I remember as a kid watching Cartoon Network, and being frustrated that other countries like England had already seen the new episodes of shows like Courage the Cowardly Dog like months before we ever got to see them.
So you'll never know before 2012 is over and early 2013 that YouTube shows one of the remaining Season 16 Arthur episodes yet to air in the USA imported/taped/DVR'd and transferend from Canadian/UK/Australian TV, especially if it is the 2 I am hoping for in early 2013 - "Fern and the Case of the Stolen Story" and "Sue Ellen Veggies Out".