With mine, my iPod Touch syncs all the music and video on it when its plugged in.
I was wary when I first got my iPhone as I didnt want any music or videos on it - yet.
But anyway, I synced the phone and nothing happened anyway, despite everything being ticked (which I didn't realise till I'd plugged in the iPhone) - it never put any music or video on to it - it never asked if I wanted to, it never gave me the option!!