Sometimes during a concert especially during a ballad or other slow
song the crowd will begin to wave lighters or other objects that give
off light.  Where and when did this ritual originally begin?

Pro Bono could probably give you the exact time, but I'd say mid
1400's, originated with Torches, and something about the villages
getting together and singing.  These lasted well into the night, and
while beer was involved, it was found to be impossible to keep the
torches still. Thus during long periods of slow singing waving a
torch, now a lighter has evolved.