I was sitting on the couch today and began watcing a cockatiel singing/chirping/talking on youtube. My cockatiel heard the sounds of the cockatiel from my laptop, ran up my leg, jumped in front of me facing the laptop, then he got all thin, his tail fanned out and he hissed angrily at the cockatiel on the laptop screen. When I closed the video he ran to me and cuddled up with me and bowed his head for a scratch. Can anyone explain this reaction/behaviour and is it a bad thing?