Hi ,
You could maybe try using View Sets in combination with Video Parts.
You would first create two view sets: one with the lights on and one with the lights off.
Then in your video, have Part 1 of the video lead up until you want the flash and assign it to use the view set with the lights off in the Video settings. Create a new Part of the video and assign it to use the View Set with the lights on. You can then create another part right afterwards which would use the view set with the lights off to continue.
The only problem with this approach would be that video parts can only be as short as 1 second, so the flash effect wouldn't be very quick.
Best,
Raghib