Welcome to the Forums Patricia.
Yes it is possible to improve your footage, although it may be a little time consuming.
1. Using the Razor tool split your video clip into identifiable clips (at each of the light changes)
2. From the Window>Effects menu apply the Brightness & Contrast effect to the clip.
3. From the Window>Effect Controls adjust the values of the Brightness and Contrast until you have the desired result.
4. If your problem is more colour based ratehr than contrast or brightness based then apply the Colour Balance video effect and adjust as per step 3.
Hope that helps a little Patricia
COMPAQ something or other with 500Gb Boot Disk, 1Tb external Firewire Disk, 4Gb Memory and a super duper sound card, 19" TFT Monitor etc etc etc
Sony TRV33e : Sony TRV310e : Canon XM2
Sony Vegas Studio editions to v11
Remember, there is always more to learn than there is to teach.