1. There shouldn't be any .flv files posted anywhere on the site if they are please post/report the links to them for removal. (They would be of low quality and not allowed)
2. If your using IQS which you did not say how your streaming the links. It would be the default JWplayer which is a Flash Player not .flv ,but you might be confused that it is. Or you using the host's embedded player which again could be a Flash Player.
3. Streaming/Downloading has nothing to do with IceFilms that is between you and the host where the file is. The host may be under heavy load or it's something on your end I.E. your computer, or ISP. Nothing Ice can do about this problem.