We have 2 camera operators, and usually a couple of unmanned cameras, on all our shoots.

This means we are able to capture all aspects of the day from the formal to the candid, for example, during the vows we can capture different angles of the bride & groom and during the speeches we can film the audience's reaction.

If only one camera was used you'd probably have a lovely shot of the bride saying her vows but only a shot of the back of the groom's head when he is saying his!

An unmanned camera could be used to get a nice "bird's-eye" view of the ceremony and would be used for the video guest book at the reception.