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
XML documents must be served with an XML Internet media type (often called "MIME type") such as codice_2 or codice_3, and must conform to strict, well-formed syntax of XML. XHTML 5 is simply XML-serialized HTML 5 data (that is, HTML 5 constrained to XHTML's strict requirements, e.g., not having any unclosed tags), sent with one of XML media types. HTML that has been written to conform to both the HTML and XHTML specifications  and which will therefore produce the same DOM tree whether parsed as HTML or XML is known as Polyglot markup