Actually this is a case of mixing up "IP" laws ... trade secrets are very different from patents, although patents were partly introduced to encourage companies to open up and to discourage the use of trade secrets.<p>Anyway ... "proprietary" means just what it says ... "exclusively owned by someone" under a trademark, patent or as a trade secret. So to say that H.264 is proprietary is actually correct.<p>On the other hand, H.264 is more open than Real Video, since you can get the specs of the format, an implementation is already available to you and the patents are currently reasonably licensed.<p>That said, the concerns of Mozilla are valid ... we could end up in the same situation as with GIF and MP3 ... although I don't think Theora has any chances to take over since it's technically inferior and H.264 is already accepted as a defacto standard (mostly because of Flash).