H.264 isn't exactly "closed" per se - the standard itself is freely available[1], which is why we have great free and open source encoders and decoders for it. What you mean by "closed" is most likely just "patent-encumbered", which it most certainly is and which affects anyone wanting to use it commercially (at the moment you can use it freely for non-commercial purposes on the internet, but this may or may not change in the future).
[1] http://www.itu.int/rec/T-REC-H.264-201201-I/en