Not sure whether to post this here but since a lot of people are asking and talking about it and since there's a news article on it already, here's some quick info:

Yonghwa fans who were at a Night After Night recording were talking amongst themselves and said: "I can't see Yonghwa. I wish Daesung would get his head out of the way" and Daesung heard them so he moved his head and the fans laughed. Then in the end, Yonghwa and Daesung ended up changing spots. This was found out by Daesung fans when they saw it on a fan cafe and it was actually one of the moderators on the site that was saying this. The Yonghwa fans were saying stuff like "Haha I guess it's one of the privileges of having a lot of fans there". A few weeks back at a Night After Night recording some rude girls were scolding Daesung for something as well during a break in recording (even though they're people Daesung doesn't know).

Translation by Flibbertigibbet @ 6theory forums