I also want to show FLV video in my DNN site and can't use the media module. (We have hundreds of flv files already created that we need to view, and do not store these in other files formats like mov)
1. Allow flv extension. Log in as HOST, change Host, Host Settings, Advanced Settings, Other Settings, File Upload Extensions to include FLV ("pdf,swf,flv,avi,wav,mov"...)
2. Upload a flv and a mov and a flv file (lookout.mov, 0002-08A.flv). As HOST or ADMIN, files in control panel, choose a folder, upload
3. Add a "Media" module to a page. Edit media options: File Location: (From step 2). FileName: lookout.mov. (Choose from the FileName drop down, where the flv file does not appear)
At this point, I gave up on the media module, assuming that .flv files cannot be played. I am considering either programatically converting the flv files to another format like mov OR trying to use a flowplayer (http://flowplayer.org) in a custom module I create. Converting the files is a waste of processing and space, and I'm not sure if a Javascript solution will work very well or at all within DNN.
Any input you can provide on playing flv files is appreciated.