A video index is a file that the Video Extender uses to find a specific shot or frame in a video clip.
The Video Extender can detect scene changes in a video. A scene change is a point in a video clip where there is a significant difference between two successive frames. This happens, for example, when a camera changes its point of view while recording a video. The frames between two scene changes constitute a shot.
You can use the Video Extender's scene detection capabilities to find a shot, or even an individual frame, in a video clip. To do this, the extender needs indexing information for the shot or frame. This indexing information is stored in an index file.