Atmospheric "sprites" captured in explosive detail

Thought this might be of interest: Atmospheric "sprites" captured in explosive detail -

"Mysterious flashes of light called “sprites", that occur above thunderclouds during powerful storms, have been captured on film in unprecedented detail by researchers using an ultra-high-speed camera."

Video was taken with 7000 frame per second cameras. Links to video in QuickTime and Real formats:

Darren Addy
Kearney, NE
Was wondering if they use film or digital. I can't imagine a 7000 fps digital camera, but I know they use film cameras like that to film explosions. The film shoots through the camera in a few seconds, so you have to time everything perfectly.

I am sure a camera with that kind of shutter speed has a high lux requirement. I wonder what was there that we didn't see!