Yeah all you need is a flash player and the flv file. I have put a copy of a flash player you can use up on my website. Just right click and click "save as" on the link below.
Free flash playerThen you just need to embed the following code in an html file and put the html, the flv, and the player file you download above in the same folder. Where you see **vid location** you can place a url or just the filename of your flv file.
CODE
<object type="application/x-shockwave-flash" width="400" height="350"
wmode="transparent" data="flvplayer.swf?file=**vid location**&autoStart=true">
<param name="movie" value="flvplayer.swf?file=**vid location**&autoStart=true" />
<param name="wmode" value="transparent" />
</object>
Again, make sure the html page with the code above, the flvplayer.swf and the flv file you want to show are in the same directory of your website. That way it will find all the files. If you don't see it work immediately it is probably because you are missing one of the files or not pointing correctly to the files using their paths.
Enjoy!