This video was taken on December 17 in Brazil near the town of Palontina. Strong light emanating from the surface is a very strange phenomena. As you can see from the photos it actually lights up the underside of the clouds. If it is a natural occurrence it is something that is inexplicable. There appears to be no known source or man-made structure giving off this light.
This video was taken on Dec 17, 2012 in Brazil. It actually shows the clouds being light from below.