Weimaraner howls to Titanic soundtrack and my extraordinary whistling skills :P

My dog Faloop the Weimaraner howls to the sound of me whistling the Titanic soundtrack.
For those who think it hurts his ears, this is not the case. A dog will distance himself from something that hurts him.
So the question is, why do some dogs react like that to whistling? Are they singing along? does it remind them of something?
Enjoy :)
Autofocus wasn't cooperating :/