It was just a fade filter. I tried that first. It didn't look good but they way they did it used better blending. I will add it to my tutorial, but I think the model would be the best. directional colored light flickering - that's what I am looking for.
Here's how they do it:
Occasional Lightning
Events
Time - LightningTimer expires
Conditions
Actions
Wait until (InCinematic Equal to False), checking every 1.00 seconds
Countdown Timer - Start LightningTimer as a One-shot timer that will expire in (Random real number between 25.00 and 60.00) seconds
Cinematic - Fade out and back in over 0.12 seconds using texture White Mask and color (100.00%, 100.00%, 100.00%) with 5.00% transparency
Wait 0.03 seconds
Cinematic - Fade out and back in over 0.12 seconds using texture White Mask and color (100.00%, 100.00%, 100.00%) with 5.00% transparency
Wait 0.20 seconds
Set RandomSound = (Random integer number between 1 and 2)
If (RandomSound Equal to 1) then do (Sound - Play LightningBolt1 <gen>) else do (Do nothing)
If (RandomSound Equal to 2) then do (Sound - Play RollingThunder1 <gen>) else do (Do nothing)