Adobe ACROBAT READER 7.0 Manual page 201

Playing movies and sound clips
You can play movies and sound clips that authors have added to PDF documents. A media
clip may appear directly in the PDF document. In some cases, a media clip plays when
you click a link or bookmark. To play media clips, you must have the appropriate
hardware and software installed. (See
Note: If you have not downloaded the full version of Adobe Reader, you cannot play
media clips. Choose Help > Check For Updates Now to install the necessary plug-ins.
You may also need to download a media player.
To play movies or sound clips:
In the PDF document that contains a media clip, click the link, bookmark, or media clip
poster. If the media clip includes player controls, click the Play button.
Setting Multimedia preferences.)