Ask the videographer what type of equipment they use and even ask to see the equipment. A professional will be more than willing to show their equipment whereas a novice videographer may be unwilling to provide information on their equipment, especially if it is old or in poor condition.
The contract should clearly indicated the time that the videographer will be filming and on location with the wedding party. Be aware that any additional time will typically be at a rate significantly higher than the contract time and will be billed separately.