I'd like the columns to take up more than the current width, but I don't think it's possible.
Embedding video is a little funky, when I went to three columns it had problems putting in the video in anything but the center 'main content column'. If I can fatten up the single main column I can use the edit html to make my own columns- ideally there would be videos in a grid 3 videos wide, or at least two wide.