The viewport as manipulator
You can use the viewport as a camera or light manipulator. To use it as a camera manipulator, select the scene camera's animation set in the Animation Set Editor, and navigate in the viewport; this adds the movements you make while navigating to the scene camera's animation set.
If your scene camera has animation but no animation set because it was created as part of a gameplay recording, you can add an animation set for it in the Animation Set Editor. Then, you can select it and manipulate it with the viewport.
To use the viewport as a light manipulator, drag the light's animation set from the Animation Set Editor into the viewport. The active camera button's label will change to reflect that the viewport is now manipulating a light.