When iOS was first released everybody and his dog was still running their own proprietary movie (container) format. Microsoft was pushing .wmv, websites used Flash, illegal sources were using .avi files.

Apple forced these sites to provide their streams in a standardized format, MP4.

It might not be the standard you want because it isn't patent free but at least it is a standard, it's not controlled by Apple and it works on just about any device and works pretty well.