Create a white matte. (FILE/NEW/COLOR MATTE). Put it on your timeline on a track above the clip you want to "flash". Right-click on the white matte. Select SPEED/DURATION. Adust the DURATION so it reads 10 frames (00;00;00;10). Press PgUp (PAGE UP) to find the beginning of the white matte clip. In the OPACITY control, insert a keyframe. Make sure opacity is 100%. Press PgDown (PAGE DOWN) to find the end of the white matte clip. Set opacity to 0%. VIDEO-2 Color (white matte) VIDEO-1 Your clip to be "flashed" This will give you a "flash" effect. You can move the white matte clip around to fine-tune where you want the flash to occur.