Broadcast video.flv from client

That's for playing a local .flv progressively. What you're talking about would look more like

my_ns.attachVideo(file://.....)

... but that doesn't work. You can only attach a camera. Even if that did work, you'd only be able to do it with .flv files in the same local directory as the .swf, which means you'd have to distribute it as a download.

why netStream.play() method say ? :

" You can play local FLV files that are stored in the same directory as the SWF file or in a subdirectory; you can't navigate to a higher-level directory. For example, if the SWF file is located in a directory named /training, and you want to play a video stored in the /training/videos directory, you would use the following syntax:
// Play a file that is on the user's computer.
my_ns.play("file://joe_user/flash/videos/lectureJune26.flv"); ""

Not directly, as the only sources you can connect to a netstream are mic and camera objects. It would be super cool if we could connect other sound and video objects to a stream, but unfortunately we can't.

You could use a sloppy hack workaround like a screen capture driver, but it would be messy for the client. The best way would be to upload the file to the FMS server, and play it over a stream.