Why don't all browser support the same audio/video formats?

Question

When we're working with videos, we have to provide WebM, Ogv, and Mp4. When we're working with audio, we have to provide ACC and Ogg (or some other combination, I am not familiar on best practice for audio).

So why is that, and whose gain is that in the long run? What is the actual reason that browser developers would refuse to agree on a single format, knowing that developers have to continue to provide all formats when implementing a video or audio content?

Answer 1

Each format is intellectual property and requires a license to decode it. Video is much the same, but is further complicated by the fact that a “video format” is actually a combination of a video codec and an audio codec, so in some cases playback requires two licenses. Some of these formats are freely licensed, but others cost big money.

Source: http://webstandardssherpa.com/ask-the-sherpas/cross-browser-audio-and-video