While the detailed information we have is pretty sketchy, it's pretty clear that SpiderPig wants to connect the A/V output from a domestic set-top box (satellite, cable, DVD, VCR) to view the content on a domestic intranet. The suggested IP video server earlier does just that. No-one mentioned streaming live TV from an external broadcast source. What's not clear from the original request if if the material should be viewed on multiple clients, or should be recoded back to video to watch on a normal TV, not is it clear what level of relayed quality is expected.
There are
countless IP Video servers on the market (the one suggested is over 5 years old, so a bit long in the tooth), some with multiple AV inputs (often used for security camera relay over IP). What distinguishes them from one another is their ability to handle multiple sources, bandwidth (which affect picture quality on the client) and the method of client access. Some provide hardware transcoder clients to connect directly to a TV, others have a PC based application to view the stream, other simply use a web browser. Of course,
Slingbox is an example of an IP Video server specifically tailored for domestic video streaming over IP and there is no reason at all not to use such a device in an intranet as much as over the internet. This may even be the most cost effective solution in this case, and is certainly targeted at a non-technical audience for ease of set up and use.
A natural extension of the IP video server is a dedicated media server, but this would replace the set-top box in that most have their own DVB-T, -C, or -S receiver(s), usually include hard disk for PVR functions and therefore have the ability to stream live or recorded material over the domestic network.