There are couple solutions available, both revolve around balancing the signal using a pair of transformers: active balun (balanced-unbalanced) and passive balun. There are number of manufacturers that make them, you could just run a search for "video balun" on Google.
The difference between the two is in distances that they will let you to cover: the amplification provided by active devices will let you run video signal as far as 1 to 1.5 miles. The passive ones will "only" yield several hundred feet (to a thousand), and the distance will depend on whether ot not you are using color. The obvious advantage of the passive balun is the it does not require additional power supply to worry about.
Dmitri Abaimov, RCDD