Actually I don't think this is what fo guang.
It is just a very ordinary weather phenomena - I had seen it
many many times before. Nothing special.
http://en.wikipedia.org/wiki/Halo_%28optical_phenomenon%29
I think we should not be overly superstitious over such things,
otherwise we will be a laughing stock in the face of scientific
knowledge.
May be science can explain how the halo is being formed but I
don't think it can explain why it always happens after the chanting
or after the 开光 ceremony. The links show it happened after 开光
ceremonies.
In fact, there is another video clip which is more convincing
but I could not find it now but I've watched it. It showed fo guang
shining on Goddess of Mercy at Putuo Shan (普陀山) during
the 开光 ceremony. I was told by the tour guide about
the fo guang during the 开光 ceremony when I went to Putuo Shan
in China. The tour guide told me he saw it himself and not only
him, thousands of people saw it.