Attach the video camera to a camera hoist so you can raise it into the air and aim it down at the scene below. You need to use a remote control for the camera while it is on the hoist. This angle works well if you don't need a lot of height for the shot.
Climb up on a ladder to give you a higher vantage point over the scene you need to shoot from overhead. Have someone hold the ladder to keep it steady while you use it to get the shot.
Use the surrounding buildings or terrain to position yourself for an overhead shot. A tall building or a cliff near your scene can provide you with the height you need for the overhead shots. This method works well when you need to tape a larger area or want a more distant shot.
Rent an airplane or helicopter to use for your shots if it is within your budget. You may need to edit out the wind noise, but these vehicles provide you with the height for an overhead shot, and the versatility of changing positions. You might also need to obtain flying permits depending on where the shot takes place.