Pop star Aaron Carter and partner Karina Smirnoff kept their top spot on the "Dancing with the Stars" scoreboard, sharing the lead with singer Mya and partner Dmitry Chaplin — ET’s "Dancing" correspondent Marie Osmond went backstage with the celebrity contestants to talk about the highs and lows of their week two performances.   Aaron and Karina were joined by some of Jim Henson's Muppets during their performance. In reference to his green suit, Aaron said, "I feel like Gumby." His polished posture certainly made him look quite the contrary to the flimsy clay figure while he glided across the dance floor. He understands that he cannot slack off in training after his early success, saying, "I feel like I can win, the opportunity is there, but it's not going to be there if I don't concentrate and I don't rehearse and I don't focus and I don't listen to my teacher."