A slidelet allows you to have an area that is sort of like a "picture in a picture" as you see on TV. Basically, you define a rollover area that triggers the Slidelet to play. Then you insert objects such as Images, Captions, Rollover Captions and Rollover Images into the Slidelet area. Perhaps the slide itself is three seconds long and pauses after two seconds. The user mouses over the Slidelet Rollover area and triggers the Slidelet. It begins to play and perhaps plays for 30 seconds. (you get to define the play time)
Hopefully that helps better explain it.
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