Comment 2 for bug 1223226

You are using very old Pitivi release (0.15) - please install latest Pitivi 0.93 (it's already in Ubuntu 14.04, if you can't upgrade to 14.04 then please add 'ppa:baltix-members/ppa' repository) and test if Pitivi 0.9x still has a default horizontal width greater than 1024 pixels.