Long Shen watched the whole recording between Lee Kibum and Bai Yunyu. He was surprised when he heard how Kibum and Yunyu deviated from the script.
Bo Yun tried to comfort Kim Tae-Oh in the script, but the lines weren't that personal. Bo Yun was supposed to say that everything would be alright, and he would be with Kim Tae-Oh through thick and thin, and that was it.
But Yunyu made it sound so personal.
Long Shen didn't hate it though, in fact, Yunyu's personal improvisation on this scene makes it sound much more sincere and alive. Since Bo Yun didn't have any family background regarding his parents, then Long Shen could easily add this background of divorced parents, so he would be able to relate better with Kim Tae-Oh.
Long Shen clapped as Yunyu and Kibum finished their first scene. This was just a voice recording though, they still had to do the scene later.