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