I got the dnn media module to play FLV files.
I took the "flvplayer.swf" from out of the zip and put it in my desktopmodules/media folder so it could be accessed by this URL, that little piece of flash will play the FLV files.
http://yourdomain.com/desktopmodiles/media/flvplayer.swf
Next you need to add the following 3 lines of code (with visual studio)
To the mediamodule.ascx.vb add the parts in bold:
Private Const RealMediaTag As String = "<OBJECT CLASSID='clsid:CFCDAA03-8BE4-11cf-B84B-0020AFBBCCFA' {2} {3}><PARAM NAME='SRC' VALUE='{0}'><PARAM NAME='CONTROLS' VALUE='ImageWindow'><PARAM NAME='CONSOLE' VALUE='one'><PARAM NAME='AUTOSTART' VALUE='true'><EMBED SRC='{0}' {2} {3} NOJAVA=true CONTROLS=ImageWindow CONSOLE=one AUTOSTART=true></OBJECT>"
Private Const FlvTag As String = "<embed pluginspage=http://www.macromedia.com/go/getflashplayer src='http://YOURDOMAIN.COM/DesktopModules/media/flvplayer.swf' {1} {2} {3} type=application/x-shockwave-flash bgcolor='' salign='LT' quality='high' menu='false' loop='false' flashvars='file={0}&showdigits=true&autostart=true&showfsbutton=false'></embed>"
Then add the bolded part a little further down....
If MediaSrc.LastIndexOf(".swf") > 0 Then
HTMLTag = FlashTag
ElseIf MediaSrc.LastIndexOf(".flv") > 0 Then
HTMLTag = FlvTag
All done editing that file....
Now edit "editmedia.ascx.vb" and add FLV to the end of the follow line of code..
Private Const MediaFileTypes As String = ",AVI,MPEG,MP3,ASF,ASX,WMA,WMV,WAV,MIDI,QT,MOV,RM,RAM,RPM,FLV"
All done editing that file....
Now compile...and put the new DotNetNuke.Modules.Media.dll in your bin folder...
Good luck took me about 10 minutes to make the mods....