Netflix has been "frustratingly" using MicroSofts Silverlight technology to deliver streaming video to web browsers on the PC and Mac. I say frustratingly because that does limit what devices you can actually run the application on and if there is not application for your platform then you can't use use the devices web browser. Silverlight doesn't work that way.
Since Microsoft announced end of life of Silverlight 5 in 2021HTML5 Premium Video Extensions:
Over the last year, we've been collaborating with other industry leaders on three W3C initiatives which are positioned to solve this problem of playing premium video content directly in the browser without the need for browser plugins such as Silverlight. We call these, collectively, the "HTML5 Premium Video Extensions"
Media Source Extensions (MSE)
Encrypted Media Extensions (EME)
The W3C Encrypted Media Extensions specification "extends HTMLMediaElement providing APIs to control playback of protected content." The video content we stream to customers is protected with Digital Rights Management (DRM). This is a requirement for any premium subscription video service. The Encrypted Media Extensions allow us to play protected video content in the browser by providing a standardized way for DRM systems to be used with the media element. For example, the specification identifies an encrypted stream format (Common Encryption for the ISO file format, using AES-128 counter mode) and defines how the DRM license challenge/response is handled, both in ways that are independent of any particular DRM. We need to continue to use DRM whether we use a browser plugin or the HTML5 media element, and these extensions make it possible for us to integrate with a variety of DRM systems that may be used by the browser.
Web Cryptography API (WebCrypto)
First Implementation in Chrome OS
We've been working with Google to implement support for the HTML5 Premium Video Extensions in the Chrome browser, and we've just started using this technology on the Samsung ARM-Based Chromebook. Our player on this Chromebook device uses the Media Source Extensions and Encrypted Media Extensions to adaptively stream protected content. WebCrypto hasn't been implemented in Chrome yet, so we're using a Netflix-developed PPAPI (Pepper Plugin API) plugin which provides these cryptographic operations for now. We will remove this last remaining browser plugin as soon as WebCrypto is available directly in the Chrome browser. At that point, we can begin testing our new HTML5 video player on Windows and OS X.
Source The Netflix Tech Blog