That is pretty friggin cool if you ask me. Looks like it was a response to the dimmed lighting in the seats that the fans don't seem to happy about, but it ended up escalating into it looking really cool. I'd be down if they keep doing that!
(But I'll bet they'll get asked to stop)
i didn't notice any dimmed lighting at the stadium, maybe broadcast they change the camera settings .... seemed pretty organic starting down the left field line and growing from there. way better than the 'wave' or beach balls at doyer stadium