It's a Flash movie that accepts FLV files as input parameters. No plugin
necessary other than Flash which I would assume you already have.
It should be made very clear that there are now 2 types of flash
movies being used. The old method only contains a swf single file that
includes the movie and sometimes added text, etc. This old method has
severe limitations for high resolution videos, so some update was
needed when one wanted flash video capable of much higher quality. The
flv/swf movie was the result. You may not be able to tell a flv/swf
format is being used from source code, as only a swf flash file is
called. As explained in my first post, the swf portion internally
links to the flv video portion th now be played alone on some players
especially made for it without a swf container file, but such special
players are not available on nearly as many computers as is flash
which was designed to play a flv using a swf container file. The main
merit that such players for flv only have is convenience for those who
rip the flv portion of a flv/swf video from sites such as YouTube,
MySpace, etc that mainly use the flv/swf format. If you also ripped
the .swf part of the flv/swf from the site, you could put up the flv/
swf video as intended, but that would not be what many who rip such
videos would want. It often would contain logos for the site such as
YouTube or Myspace and it often would contain ads and links back to
various servers, etc.
In addition to re-encoding a flv to produce a flv and swf file pair
that matches it, there are programs to convert an isolated flv to
other video formats such as wmv.
It might help to view the code for a flv/swf movie at my site at
http://www.cwdjr.net/flash/Fatty.php . Notice that there is no
reference to an flv. Although the flv is on the server, the swf
container file you link to takes care of linking to the flv
internally. Also I am using object code that validates at the W3C.
Many still use embed code, etc that is not valid, but often will work
anyway. This code allows playing on most recent browsers from IE,
Firefox, Opera, etc provided of course that the computer has flash
installed. If the flash people are to be believed, it is installed on
far more computers than players for any other video formats. However,
one can offer an assortment of file types at various bit rates to pick
up more viewers that have only support for .wmv, .rm, .mov, etc
formats. For video haters and those with extremely slow connections,
you can always offer a jpg from the movie or text when the movie
format is not supported if you wish. Or in many cases, if the movie
format is not supported, It just does not appear on the screen of the
monitor, and a viewer will not even know a video was included unless
the source code is viewed.