Two years ago, a surprising post from Chromium's blog announced that Google Chrome will drop support for H.264 HTML5 videos. "Though H.264 plays an important role in video, as our goal is to enable open innovation, support for the codec will be removed and our resources directed towards completely open codec technologies."
Nothing happened since then, so I assume that Google changed its mind. Mostly likely, Google hoped that this announcement will increase WebM's adoption, but that was wrong. Other than YouTube, few other sites converted their videos to WebM. Why spend time and money to convert videos when they could simply use a Flash player?
After all, Adobe Flash doesn't support WebM and that's the second broken promise: "As Kevin Lynch mentioned today at Google I/O, we are excited to include the VP8 video codec in Flash Player in an upcoming release, which will help provide users with seamless access to high quality video content on all of their Internet-connected devices," announced a blog post from 2010.
Adobe didn't support the VP8 codec, so Flash is still mostly H.264-only. And so are Internet Explorer, Safari, iOS, Windows Phone. WebM is mostly non-existent in the mobile space and that's where the future lies. Even if Android 2.3+ supports WebM, there aren't many devices with hardware acceleration for WebM.
Now Firefox's Windows nightly builds allow you to play H.264 HTML5 videos using the Windows Media Foundation backend. "That means if you're using a Windows computer that already has a licensed H.264 decoder installed, you'll be able to enjoy HTML5 video that's been encoded using MPEG LA's codec."
That means in the near future the most important browsers will support H.264 videos natively and WebM will matter even less. There's a VP8 successor that's more efficient, there's WebP for images and there's the WebRTC API for native video chat apps, but H.264 will continue to dominate web video. Those broken promises just made it more obvious.