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.
Comparison of HTML5 and Flash
Until 2008, the use of Flash was covered by restrictive licenses. The conditions prohibited use of the specification to develop any software (including players) which could render or read (and thus convert) SWF files, and required the output SWF files to be compatible with Adobe's players.