Video: Gangnam Style's Psy, One Direction more than overnight successes 

In this photo released by Warner Bros., talk show host Ellen DeGeneres, center left, joins Korean pop star PSY as he performs his super hit Show caption
In this photo released by Warner Bros., talk show host Ellen DeGeneres, center left, joins Korean pop star PSY as he performs his super hit "Gangnam Style" during a taping of "The Ellen DeGeneres Show" on Tuesday, Sept. 18, 2012 in Burbank, Calif. This episode of "The Ellen DeGeneres Show" airs on Wednesday, Sept. 19. (AP Photo/Warner Bros., Michael Rozman)

Gangnam Style's Psy, One Direction and Carly Rae Jepsen are being called overnight successes by the media. The chart-topping pop stars, however, are enjoying huge hits now but their careers have been years in the making.


Gangnam Style's Psy, One Direction and Carly Rae Jepsen are being called overnight successes by the media. The chart-topping pop stars, however, are enjoying huge hits now but their careers have been years in the making.