A 4 channel passive video balun is defined as a specialized electrical transformer that converts electrical signals that are balance about ground (differential) to signals that are unbalanced (or single-ended) and or converts signals that are unbalanced to balanced.  In that manner they are used as devices that are used to connect lines of different impedance.  Balun is derived from two separate words; BALance and UNbalance (BAL+UN).

Wow!  That was quite a mouthful.  Let’s redefine the definition without the overly technical phrases.  Simply put, any wire or cable has a natural resistance when electricity is applied.  Consider this, what if you took a typical AAA dry-cell battery and connected a wire to each end of the battery.  Now, what if the wire you attached was 5 miles long.