I wouldn't refer to it as trivial, would she still be liable for copyright infringement if she sent a copy to her friends and family? If it is deemed copyright infringement any copy and even possibly her own original copy would be infringement wouldn't it?
From previous articles I have read if I remember correctly it was playing on a radio or CD player. Since the kid was dancing to the tune I'd assume it wasn't dubbed.
From my understanding you can't legally use tracks of music you own on CD for your own personal use in videos. Burn it as MP3 and play it on your DVD player and your legit, put it to video and you're breaking the law. Just goes to show how asinine many of these laws are.