YouTube will need to keep its h264 files for Flash (and mobile devices), so Ogg would require petabytes of new storage space. Real money. According to YouTube's engineers to get comparable quality video with Ogg the file size will have to increase. Real money.<p>If it would be cheaper there would be no reason not to do it. Google built support for Ogg into Chrome, so they aren't scared of the format. They aren't doing it so I'm going to go out on a limb here and say it's not cheaper.