Found the fideo while brousing throu youtube.The quality is bad but you can hear the sound clear.In the discription was written:
He talked about how he couldn't focus and tears wouldn't come down during crying scene so he said he took a break for a sec and sat alone on a bench. Then Yoo In Na came along and sat next to him and put an earphone in his ear. It was their drama's ost. Then at that moment, tears started running down his face (he said). And then he says some stuff (not important) and then he says something like, "I want all of you guys to know.. that I love Yoo In Na." and then there comes the screams lol.