In broadcasting, playout is a term for the transmission of radio or TV channels from the broadcaster into the networks that delivers them to the audience.
http://en.wikipedia.org/wiki/Playout --from Wikipedia
There are a number of ways to do this:
Over a couple of years, z! has built a number of ZVideoServer video server? systems for use at conventions. They are all x86-based PC systems running http://www.freebsd.org/ FreeBSD. These can be built for fairly little money, especially compared to commercial systems, and while not having all the bells & whistles, some of which are actually really useful, they will work.