We have all had the situation where we need to cover a cut but have no b-roll. The flash cut is a trick that is (over)used. But, when in a bind, you might as well make it look like a real flash instead of just a few frames of white...

Go to your viewer window and down to the icon with an "A" on it (the lower right). Go to Matte and then Color.

Click on the Controls tab.

Click on the color box.

Choose white by moving the slider almost all of the way to the top. (Out of habit i do not move it all of the way to the top so as not to go above 100IREs, which will be another topic some day).

Go back to your Video tab.

Highlight the length box and type in: 06 and hit the Enter key on your keyboard. This makes the length of the white flash 6 frames, but it will be shorter to the eye...just keep going.

Now click in the the viewer screen (on the big white box) and drag that down to your Timeline so that it "covers" your cut point.

At the bottom left of your Timeline is the opacity bar (it looks like mountains or little mice noses if they were rubbing ears). Make sure it is selected.

Select the Pen tool by clicking on it in the tool box or just pressing "p" on the keyboard.

Using the pen tool (I am zoomed all of the way in here) place 4 points were you see them indicated here. Frame one is set to 0%, frame 2 is set to 100%, frame 3 is set to 100%, and frame 6 is set to 0%. This gives the effect of fall off, like when a real flash blinds you. ALSO NOTE that the 3rd point is covering my cut point. The cut must be under a 100% opacity point or else you will see the cut, which defeats the purpose.

This is what it looks like...use your arrow keys to move the playhead back and forth to see the effect slowly.