Light Streaks

Hi,

I recently saw a tutorial about creating light streaks as seen on the ipod nano advert.
I’ve followed the tutorial and created my light streaks although I now wish to have these streaks floating around a different background other than black
for an animation I’m working on. If I try dropping in a different background these streaks disappear. Do you know how I can place this effect on a different background?

I would be most grateful for any help/advice.

Thanks in advance,

Matt.