I also suspect that communication and data were cut off to the ground at least several seconds before those video clips were recorded. Try 3 minutes for any video captured in the Dallas area ...
(20 seconds from horizon to horizon - YOU do the math.)
Good point. I was completely unaware of exactly where in the sequence of events the video image was recorded. I thought it was closer to the actual break-up because there is not yet any visible contrail at the start.