No no no, you're making the assuption that "buying an licensed encoder off the shelf" gives you some kind of patent license. It does not. It's a license to run the software from the manufacturer of the software. It sometimes contains a transferable license from the patent holders, for some purposes. Read carefully.
But walking into Fry's and buying a codec product off the shelf for $49.95 doesn't automatically allow you to start a video megasite.