Encrypted Media Extensions
Netflix supports HTML5 video using EME with a supported web browser: Chrome, Firefox, Microsoft Edge, Internet Explorer (on Windows 8.1 or newer), or Safari (on OS X Yosemite or newer). YouTube supports the HTML5 MSE. Available players supporting MPEG-DASH using the HTML5 MSE and EME are NexPlayer, THEOplayer by OpenTelly, the bitdash MPEG-DASH player, dash.js by DASH-IF or rx-player.
HTML5 video
Although Theora is not affected by known non-free patents, Apple has expressed concern about unknown patents that might affect it, whose owners might be waiting for a corporation with extensive financial resources to use the format before suing. Formats like H.264 might also be subject to unknown patents in principle, but they have been deployed much more widely and so it is presumed that any patent-holders would have already made themselves known. Apple has also opposed requiring Ogg format support in the HTML standard (even as a "should" requirement) on the grounds that some devices might support other formats much more easily, and that HTML has historically not required particular formats for anything.