How is this done?

[Screed]

http://www.youtube.com/watch?v=IWMsCyGNNiw&feature=plcp

In the beginning where that flashing is coming from the top to the bottom constantly, how is that done in Sony Vegas?

To me it kinda looks like the flash is a duplicate of the mask but it's a lighter colour and then just positioned in pan crop to make that transition from the top to bottom of the screen. But Idk, it's kinda hard to tell. So any ideas?

[Eake4]

First light can be done in TV simulator effect while the rest are done like how you thought of it.

[Screed]

Thanks a lot! I really couldn't figure it out.