How can you play flv files with windows media player 11?

You need to download FFDShow, install it then in the FFDShow program I think you enable codecs. Then download FLV Splitter and install, once done, click the close button and now open the flv file, if you can't be bothered just download VLC Media Player.
another option is .... u need to navigate to http://media-convert.com/
choose the input file ( either local in your PC or online using a URL )
select the output file format and
agree to the terms of service
click OK button to fire away.
wait until conversion if finished then click download to save it locally to your PC.
Note: If you are using script-disable add-ons for Firefox (free) or IE (IE7 requires a valid license of Windows XP) turn it on for only media-convert.
another Note: I am not associated with the site at all.