I don't know if you can alter gamma using the SE version of Studio (but since it's a basic effect, it's probably enabled), you can definitely do it with the full (standard) version, but I'm telling you it rarely gives good results (it will add lots of grain to the footage) so try to avoid shooting poorly lit video anyway ( sorry I couldn't help it). Still, are you sure the video is insufficiently lit and it's not just a bad calibration of your TV/PC monitor?