Often when making cuts between shots that contain several sources, there's a quick flash. I've noticed I can sometimes rearrange the order of the sources to eliminate the flash, but in some cases, the flash persists.
You could watch our show live right now to see the flash. twitch.tv/hyperrpg. I can give you a Youtube example later. You'll notice every time we make a switch, there is a flash. By white flash, I mean a frame of solid white. Sometime it covers the entire screen. Sometimes it only covers one particular video source.
In the instance of switching between two shots and keeping layer order consistent, it's not possible when I'm switching between a shot that is two cameras and a shot that is three cameras. I've added a camera. Where does that extra camera go? I thought that maybe I could add that third camera into the two camera shot and turn it off so that it's not visible, but the flash is still there.