Flashing light effect

[Poolboy]

What is the best or easiest way to achieve a flashing like effect like you see in many music videos?

Example

[Midnight Blue]

In this particular example it is real strobe lights set behind really big screens inside a big aircraft hanger but you can use little bits of white media to simulate this effect. Just put it above the main video track put a slight fade in and out. You might want to reduce the opacity, it all depends on the look you're after.