Yes. The script is found in the mediavps, mv_exp-sct.tbm in mv_effects. Its behaviour is controlled by the config data found in data\config.
I think that split/one-second flash comes naturally in big explosions, like ships blowing up and stuff if you're close enough to it. It's barely noticeable with the Eos though, but...maybe it's something in the weapons.tbl.
No, it's a special script in Blue Planet, later ported to the 3.6.12 MediaVPs.
By which he means, the script was originally used in BP2, but got integrated in the 3.6.12 MVPs during development.
Hmm I see, BP must contribute quite something to the mediaVPs.
That script was the major thing. Most contributions are actually codeside, as Battuta, Darius, Axem and Esarai are notorious for doing stuff that breaks the engine.