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.
SubRip
A format originally called WebSRT (Web Subtitle Resource Tracks) was as of October 2010 being specified by the Web Hypertext Application Technology Working Group for the proposed HTML5 codice_5 element. It shared the codice_1 file extension and was "broadly based on" (parts of) the SubRip format, but was not fully compatible with SubRip.
The prospective format was later renamed WebVTT (Web Video Text Track).
Google's Chrome and Microsoft's Internet Explorer 10 browsers were the first to support tags with WebVTT files for HTML5 videos. Mozilla Firefox implemented WebVTT in its nightly builds (Firefox 24), and as of Firefox 31 (July 24, 2014), Mozilla enabled WebVTT on Firefox by default. The feature had to be enabled in Firefox by going to the "about:config" page and setting the value of "media.webvtt.enabled" to true. YouTube began supporting WebVTT in April, 2013.