How to white out screen with a flare I am trying to do a short video intro. The camera will follow a straight path through a circle, then I want the screen to flash completely white. 

I have the camera set up to follow the path. Now how do I make the screen flash white?

I just want the screen to go completely white. Doesn't have to be fancy right now. I guess from a circle in the middle that quickly grows to fill the screen.
This can be done very easily in the compositor. I am using the Cycles node set in this example.

First, press Shift+A and add an Ellipse Mask node.



Do the same for a Blur node.



Then hook up the nodes as shown. Animate the Width and Height values by keyframes to animate the effect.



Depending on your render size you may need to adjust the blur size, but this should get you on the right track.