Zencoder
Zencoder is the creator of an open-source HTML5 video player, Video.js, built with Javascript, HTML, and CSS. Video.js plays video via native playback in all HTML5 browsers and devices, or through Adobe Flash when HTML5 playback is not available.
HTML5
HTML 5 is the fifth and current major version of the HTML standard, and subsumes XHTML. It currently exists in two standardized forms: "HTML 5.2 Recommendation" by the World Wide Web Consortium (W3C, a broad coalition of organizations), intended primarily for Web content developers; and "HTML Living Standard" by WHATWG (a small consortium of four browser vendors), intended primarily for browser developers, though it also exists in an abridged Web developer version. There are minor conflicts between the two groups' specifications.