There is a wide selection of the equipment that allow different video signal to be transported over LAN cable.
Let's consider you have that 400 ft of direct cable between the signal source and the display device (no active equipment like Ethernet switches in between those points).
In this case you will just need a suitable video to UTP adapter on the both ends of the connection. On the signal source end it converts the normal video signal going on 75 ohm coaxial cable (1-5 coaxial conductors depending on video signal format) to 100 ohm balanced twisted pair. On the receiving end you have other converter that converts from 100 ohm balanced twisted pair back to 75 ohm coaxial cable. That will do the job for analogue video signal format.
There are both passive and active converters for doing the conversion. Generally active devices perform better and cost more and they need power.
Passive devices are usually cheaper and do not need any power, but generally their performance is somewhat worse than what best actived devices give (for many cases passive devices perform just well enough).
Here are some links to information on products that can transport composite video over LAN cabling:
http://www.epanorama.net/phpBB3/viewtop ... 2&t=136517http://www.epanorama.net/phpBB3/viewtop ... 2&t=130013Here are more links to similar products:
http://www.dealextreme.com/details.dx/sku.22236http://www.dealextreme.com/search.dx/se ... eo%20balunIf you have need to transport other analogue video signal formats (S-video, component video, RGB, VGA etc..) then you need other type of converters designed for those video formats. They are more expensive but should be quite widely available.
There are also converters for digital formats like DVI or HDMI if you use those interfaces, but those are uusally quite expensive and need a pair or CAT5 cables (two RJ-45 outlets wired between those locations).
There is more useful information and links on this topic in this site here:
http://www.epanorama.net/links/wire_av.html#utpvideo