It looks like Rain, who appeared on the compilation, was jealous of Daesung at Coachella.

I was watching the compilation video uploaded yesterday, and it was hilarious having Rain as a guest.
Daesung mentioned the performance at Coachella last month where he displayed Korean text and sang Trot.
He said that while watching the performance, he was incredibly surprised and also felt a sense of pride, so he was envious.
Rain also said that he wants to try a stage where he really shines in Hangul later on, and I can really relate to that.