video over cat5e

If that isn't feasible you need to add Repeater Stations in the run to boost the signal so every 150 to 200 Feet add a Switch or Hub depending on what you currently have installed.

While a Switch would be the best option a hub will suffice if required.

Or you could change the CAT 5 to Fibre Optical which supports much longer runs before you start to get any signal degradation.

Col

Put a balun at each end, and just use a single twisted pair of your cat5. That gives you another 3 pairs for whatever you want (i.e. 3 channels of audio.) Because the signals will be balanced, noise would be minimal. You shouldn't need to boost your signal either.

See this link for more info:

http://www.dplay.com/dv/balance/balance.html