Best Way to Load Streaming Media Content in Intranet

The NSC File is what tells the player the encoding format and other specifics about the stream. This is necessary because the player is receiving a multicast stream so there is no handshake with the server or any exchange of information. The server is just pumping out bytes to everyone and the player could tap into this stream of bytes at any point so it needs to know what it's getting to make sense of it.

Jon Lech Johansen wrote a blog post about decoding NSC files that might aid you in creating your own but unless you have a specific need, it's going to be far and away easier to just run the Multicast Announcement Wizard in the SMS interface. If you want to do something programatically then look at Microsoft's Windows Media Services SDK, there's an API call for announcement files.

It's probably packet loss. Are your switches optimizing multicast or just flooding the traffic out all ports?

You can transcode the stream - I use something like

#transcode{vcodec=h264,venc=x264{keyint=15},acodec=mpga,vb=2500,ab=128}:std{mux=ts,access=udp,dst=x.x.x.x}

keyint specifies how often to put a keyframe in the stream - the lower it is, the better the stream will recover from dropped packets in my experience.