Can anyone tell me at what convention did Jensen Ackles describe how he did not want to act in the final scene of "about a boy" in which Dean was supposed to smile and like the "song shake it off" bởi Taylor Swift?

I saw a clip in which Ackles stated that he had to be coaxed into and initially would not do the final scene of "ABOUT A BOY" where Dean turned on the radio and heard Shake it Off and smiled and seemed to like the song. I just cannot remember what Convention that was at and would like to view the clip again.