Forbidden Access But Yet FLV Plays Properly and Successfully

Our site's been installed with Open-Source Flowplayer for playing flv, ie flash videos. This was all fine. But when we create access restrictions to subfolder or folder that contains all the flvs (to prevent download of the files from the folder by our site audience), then flv cannot be played and we get the following error message: "200, Stream Not [login to view URL], clip:'[Clip]'[login to view URL]" Alternatively, we loosen those folder access permissions, and all of a sudden the flvs play successfully. But we want both twin goals to be achieved, as we want to prevent download of flvs by our site audience, while enabling the flvs to play successfully on their PC. Who DEFINITELY can solve the problem WITHOUT SPECULATIVELY BETTING HERE ?