The FLV file format, which has been supported since Flash version 7, is the preferred file format for delivering video clips via Flash. FLV files cannot be played back directly; they must be embedded in (or linked from) an SWF file. You create (or download) a "container" SWF file from which to play the FLV file. The most common approach is to use an SWF file that functions as a media player with screen and playback controls (see Figure 2).
Figure 2 Flash FLV file embedded into a container SWF file with a playback control "skin"