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
HTML 5 is designed so that old browsers can safely ignore new HTML 5 constructs. In contrast to HTML 4.01, the HTML 5 specification gives detailed rules for lexing and parsing, with the intent that compliant browsers will produce the same results when parsing incorrect syntax. Although HTML 5 now defines a consistent behavior for "tag soup" documents, those documents are not regarded as conforming to the HTML 5 standard.