Plain and simple, Film Flash is an automated, dynamic preset for After Effects that bumps up the exposure of the footage to create a cool transition effects between two video clips. All you have to do is add a layer marker right at the point of transition, and Film Flash does the rest. The effect is highly customizeable and has many additional uses. The video explains it all.
THe preset, created by Dan Ebberts and Aharon Rabinowitz, can be downloaded here: