I am just finishing up my portfolio website and one of my pieces was a LightWave animation that I saved out as a .mov file. I used the Flash Media Player to convert it into a FLV file and add the playback controls. I imported the FLV files into my Flash document and when I tested the movie everything worked fine. Once I published the Flash document, loaded everything to DreamWeaver and uploaded everything online, The place where the FLV file usually played was blank. I loaded the FLV file online along with my SWF site. I'm sure it's something simple but I could really use the help. If you need anymore information from me just let me know, thanks a lot!
Was the FLV in the same folder as the FLA (or a sub-folder) when you imported it? If not, then it is likely that Flash used an absolute path to the FLV on your hard drive - which is a path that doesn't exist on the server. Check the "source" in the parameters tab to be sure it is a relative path.
If that is fine, then check that the server has the FLV MIME-TYPE set-up. If you don't control your server, check with your webhosting provider. Ask them if the hosting that you have is able to serve FLV files.