Its definitely not coldplay - fix you. They were only young members in this group.
I remember the song being sung by a boy group, I believe they are brothers it doesn't seem like as if it the Jonas brothers, since I can't find any songs to match.
However I remember in the video clip there were a trail of lights hanging from a pole and I think in the lyrics the words light were sung, or maybe that was just the setting of the song, its going back at least a few years ago, it was recorded at night time if I remember rightly so, it was all based around a string of lights.
Thank you.