I watched the last two episodes of Dream High again today. This clip was very suitable for posting. It’s IU’s character Pil-suk, who sings the song Dreaming. This is the song that IU changed the lyrics for on YHY’s Sketchbook.
The clip doesn’t contain any big spoilers, but since it’s the second last episode it’s a bit of a spoiler to see where the characters are at. Speaking of spoilers, the English subtitles on the DVD give away who “K” is a little too early in the final episode (they use “her/him” when referring to “K”).