The Asia Song Festival 2009 was held last September 19. The show featured singers from Korea and other Asian countries. I'm wondering why the Philippines didn't send any representative this year....
Anyway, I also found out from Lee Da Hae's thread at soompi that she was the host of the show.
Here's a video clip of 2ne1's performance. You'll also get to hear Da Hae's voice in the background while the group was accepting an award.
Beautiful Lee Da Hae (of the korean series, My Girl) hosting the Asia Song Festival 2009