This camera adjustment allows you to match the hues of one camera with those of another. The theory behind the action - Before we begin, let's explore what it is we're trying to do. The cameras send their sync and pictures back to the switcher to be combined. Some camera cables are longer than others, delaying the signal. Some cameras get their genlock or external sync secondhand, perhaps looped through another camera, delaying the sync, thus delaying the output picture.
Some cameras process their signals more slowly than others.
For whatever the reason, the signals are unlikely to arrive at the switcher exactly in step just by luck. No big problem. Subcarrier is similar. A sample of the subcarrier is added to the back porch part of sync and is used as a reference against which to make comparisons. The subcarrier reference is called burst.