Producer and musician Yoo Hee Yeol revealed the story behind casting actor Yoo Yun Suk for his "Three People" music video as well as his and Sung Si Kyung's weight during a recent airing of 'Toy Radio'. 

When talking about Yoo Yun Suk, Yoo Hee Yeol said, "I wanted Yoo Yun Suk to take the lead role for the MV. Yoo Yun Suk was also willing to participate." Yoo Hee Yeol then jokingly added, "Then he asked who was the female lead role. At that moment, I knew he was a really good person." 

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On the featuring behind his seventh album 'Da Capo', Sung Si Kyung, who featured in Yoo Hee Yeol's title track "Three People", asked the producer how much he weighed.  

Yoo Hee Yeol answered, "From what I know, I weigh 59 kg (~130 lbs). It's true that I am thin. While working on my recent album, I lost around 2 kg (4~5 lbs). Since I'm a ballad singer, I have to maintain a girl group figure. So I'm around 57 kg (~125~126 lbs)."

He then humorously revealed Sung Si Kyung's weight during the recording. Yoo Hee Yeol said, "Sung Si Kyung's foot size is 340mm (~13 in). He's enormous. From what I know, he weighs around 118 kg (~260 lbs). If you see him in real life, it's amazing. The reason why he looks like a human on TV is because he wraps duct tape around his body."