What does the Bookmark button do?
While recording an event, use the Bookmark button to mark a point for later reference while playing back. A red flag icon is displayed briefly on the screen to mark that point in the video. To see it at a later time, play back the recording to find it.
Example
An officer is recording an event while following a suspect. The suspect throws something out of the car's window. The officer presses the Bookmark button to mark that point in the video. The officer can then find that bookmark while Reviewing the event on the 4RE, or during playback in Evidence Library or Evidence Library Express.
(source: WKB-000014)