these are called overdone sapphire glows. ;)
Do you have any glow filters? Sapphire really does have a great glow effect. If you don't have a glow effect, you can stack a blur and a brightness together.
I like to flicker it a little before the transition, which is a bigger flash. These are just keyframes with size, threshold and brightness. Fun to play with.
often, I will use a quick 4 frame dissolve with the glow on the track above it as a transition. Depending on light sources on a shot, you can really come up with some cool stuff. As with CSI, it's a great way to play with jump cuts and chopped up dialog.
