I think there's no sense in streaming a certain file if we are not watching it. IMHO if the stream is happening during play/preview its ok but after all it should stop. Feature not needed and was better if not re-added...
Well there are borderline cases where this is usefull: 1. user wants to use a player that can not play from a URL 2. user wants to have an extended preview on a file that downloads to slow for streaming (ed2k) I think this are rate cases but it does not heart to have them covered.
Anyway we could make another status with right click for that. Even for forcing I think another file status is needed, not a tick/untick, to recognize it in filelist without check per-file.