These have been rumored to exist for decades, but never photographed. Scientists did not believe that they existed. Now amateurs with off-the-shelf equipment can snap them quire often.
Also, scientists denied that amateurs seeing “flashes on the moon” where meteors may have struck were crazy. Then, they were photographed by several people.
Related phenomenon: stepped leaders, upward leaders, streamers, dart leaders, and return strokes
“Recent advances in video equipment allow videographers to capture high speed images of lightning. These cameras are capable of capturing many stages of the lightning flash that the human eye cannot discern.
When played back in slow motion, stepped leaders, upward leaders, streamers, dart leaders, and return strokes can be seen.”
http://www.lightningsafety.noaa.gov/science/science_slow_motion_flashes.htm
The grant-grabber crowd of only believes in Gore-bull Warming and vivisection of human babies.