Yes you can edit your video lighter.
For example in PC with Windows XP you can easily do this with Moviemaker.
Just get the clip on editing board and select the right video effect.
This, however does usually not make the video look much better. Also enlargening the clip usually makes the quality only worse.
The key factor in digital video recording is the light. The more light you have when recording, the better quality will the video be and thus it will be much more easily edited.