The actual player (flvplayer.swf and mp3player.swf) are automatically set when inserting a FLV- or MP3-file downloaded from the media manager.
To open a video as inline popup (editor function) the script
<script src="includes/javascript/player/flvvideobox.js"></script>
must be inserted into the header of the page.
The most sensible one uses when needed the "javascript embed" because there will probably be only a few pages video editor feature. Alternatively, of course, are also the possibilities of lightbox integration.