Lightning definitely not a local phenomena
"That sounds very interesting but unfortunately would not be covered by our mandate."
Update 2018-09-25
The Global Climate Observing System (GCOS)—a group that seeks to ensure that data necessary for climate studies is made available to the public— has recently decided that lightning is an "Essential Climate Variable". To their credit they put out a public request for ideas on the goals of including lightning. I wrote them, suggesting that real progress will come from studying lightning on Earth as part of a larger circuit that extends beyond the Earth. Mr Valentin Aich kindly wrote back saying they already had that covered as they have experts on the Global Electric Circuit. I replied that I am not saying *global* circuit, I am saying *solar system* circuit. To which the reply was, "That sounds very interesting but unfortunately would not be covered by our mandate."
https://eos.org/project-updates/lightning-a-new-essential-climate-variable
We are stuck thinking that lightning on Earth is like a Van de Graaff generator, whose belt is turned by the wind. All planets are immersed in the larger electrical environment of their solar system.
Original Post
Seeing this lightning strike start, and then spread over several states, it looks like a larger version of how individual lightning discharges happen. The unfolding pattern you see in the video might be taking place over a few inches, a few hundred yards, or, as in this case, over several hundred miles.
https://www.facebook.com/NOAANESDIS/videos/1834027923304143/
We tend to think phenomena are local, and not global. If I get a speeding ticket, I am convinced it was something I did this one time and not the fact that I speed every day on that one stretch of road. We have been trying to describe lightning as a local phenomena - looking at updrafts in a particular place. That question is not wrong, as it is incomplete. Here is an associated video of thousands of lightning strikes along a weather front at the same time.
https://www.facebook.com/scottskomo/videos/1572177856135459/
For centuries we also described weather locally. The concept of a large scale weather forecast did not much exist in the West until the railroads and telegraphs broadened what we could perceive. Compare that to now where we see ONLY weather maps shown for whole continents. Everyone now knows that, yes the weather that is happening in my yard is certainly the result of local forces, but that I would not be having these local forces were it not for the giant pressure front that is working its way up the Eastern seaboard.
When I see lightning, do I think it is caused by local updrafts, by a storm system moving across states, or because the entire Earth is in electrical tension between ground and sky, or because the entire Earth is immersed in the larger electrical environment of the solar system?