Your uploaded and embedded FLV videos, when they are not set to autoplay AND you have auto-hide controls, will always show the very first frame of the video in its placeholder.

We recommend you one or more of the following if this effect is not desirable.

• Set the video to autoplay so as soon as the page is loaded the user will see the video playing
• Uncheck AutoHide Controls so the user will see video controls and recognize the object is a video that needs to be played
• Edit your video so the very first frame is a still image from the video itself.  Choose a still image that well represents that video and perhaps put a PLAY button overlaying that image so end users know it is a video.

See this article for more information on how to upload and embed FLV and other rich media