After you have the digital video in compressed format and have captured onto your computer’s hard drive, editing can start which spans two basic functions – database management and rendering. The database management aspect means keeping track of where your various scenes are, how long you want them to be, and then in what order you want them to play back in. The kind of thing which we call time line. When you edit a scene , actually you are editting the time line – deciding where the scene begins and ends, you are not really changing the scene at all. You are simply telling the editing software’s database to keep track of these new video locations and use them when playing back the video. This is why it is easy to change your clipstart and end frame or in and out frame, as well as to create alternate versions of the same clip. When you edit your video together, the database then keeps track of which scene should be played first, which should be played second, and so on. If your entire movie consisted only of cuts, the video would not have to change at all. The database would simply have to keep track of all the in and out points, as well as the playback order of the trimmed scenes.
Because it is just a database of play commands – not an actual video file, it is easy to re-arrange the scenes over and over again until you get them just right as per your plan of edit.