PetaPixel has an article about some incredible high-speed lightning video. And they link to the goods!
Incredible High Speed Video of Lightning Captured at 11,000 Frames Per Second
Here's the clip posted to YouTube.
Incredible Slow Motion Lightning Strike! (1 sec. = 3 min!)
I had never seen the "sparkling" high in the clouds as the stroke develops. So much randomness before a channel is established. The things you can see with high-speed video!