Mpeg color correction

This past weekend i went to a wedding and recorded a bunch of videos. it was pretty dark so as a result the videos were also. If i open the files with WMP all i have to do is adjust the brightness level +15 and i can see everything perfectly,however, ive tried editting the files by raising the brightness level with movie maker and countless other programs and cannot repeat the same effect as i get by simply raising the brightness bar a couple notches in the media player. I really need some help so i can get these videos looking allright and out to the bride.