Mozilla today launched Firefox 37 for Windows, Mac, Linux, and Android. Notable additions to the browser include HTML5 playback improvements on YouTube for Windows computers, and improved download performance for Android devices.

Firefox 37 for the desktop is available for download now on Firefox.com, and all existing users should be able to upgrade to it automatically. As always, the Android version is trickling out slowly on Google Play.

Mozilla doesn’t break out the exact numbers for Firefox, though the company does say “half a billion people around the world” use the browser. In other words, it’s a major platform that web developers target — even in a world increasingly dominated by mobile apps.

In Turkey, Firefox is getting a big change. Like in Russia, Belarus, and Kazakhstan, Yandex is now the default search provider for the Turkish locale.

Desktop

Firefox for Windows is gaining improved support for HTML5 playback on YouTube. While Firefox users see the HTML5 video player by default for most videos, the browser doesn’t support all the features that YouTube requires.

Here is what Firefox used to support, according to YouTube’s HTML5 page:

Here is what Firefox 37 supports:

In other words, Media Source Extensions (MSE) has been added. This W3C specification allows JavaScript to send byte streams to media codecs, allowing for client-side prefetching and buffering code for streaming media entirely in JavaScript.

Here’s the full Firefox 37 changelog:

New: Heartbeat user rating system – your feedback about Firefox.

New: Yandex set as default search provider for the Turkish locale.

New: Bing search now uses HTTPS for secure searching

New: Improved protection against site impersonation via OneCRL centralized certificate revocation.

New: Opportunistically encrypt HTTP traffic where the server supports HTTP/2 AltSvc.

Changed: Disabled insecure TLS version fallback for site security.

Changed: Extended SSL error reporting for reporting non-certificate errors.

Changed: TLS False Start optimization now requires a cipher suite using AEAD construction.

Changed: Improved certificate and TLS communication security by removing support for DSA.

Changed: Improved performance of WebGL rendering on Windows.

HTML5: Implemented a subset of the Media Source Extensions (MSE) API to allow native HTML5 playback on YouTube (Windows only).

HTML5: Added support for CSS display:contents.

HTML5: IndexedDB now accessible from worker threads.

HTML5: New SDP/JSEP implementation in WebRTC.

Developer: Debug tabs opened in Chrome Desktop, Chrome for Android, and Safari for iOS.

Developer: New Inspector animations panel to control element animations.

Developer: New Security Panel included in Network Panel.

Developer: Debugger panel support for chrome:// and about:// URIs.

Developer: Added logging of weak ciphers to the web console.

If you’re a Web developer, you may want to get more details at the Firefox 37 for developers page.

Android

Firefox 37 for Android isn’t a huge release by any stretch. The biggest improvement is probably a new back-end for the download manager, which Mozilla says should result in improved download performance.

Here’s the full Firefox 37 for Android changelog:

New: Locales added: Albanian [sq], Burmese [my], Lower Sorbian [dsb], Songhai [son], Upper Sorbian [hsb], Uzbek [uz].

New: Yandex set as default search provider for the Turkish locale.

New: Improved download performance with new download manager back-end.

New: Improved protection against site impersonation via OneCRL centralized certificate revocation.

New: Opportunistically encrypt HTTP traffic where the server supports HTTP/2 AltSvc.

Changed: URL bar now displays page address instead of page title by default.

Changed: Disabled insecure TLS version fallback for site security.

Changed: Extended SSL error reporting for reporting non-certificate errors.

Changed: TLS False Start optimization now requires a cipher suite using AEAD construction.

Changed: Improved certificate and TLS communication security by removing support for DSA.

Changed: Android home screen shortcut now opens existing tab instead of new tab.

HTML5: Added support for CSS display:contents.

HTML5: IndexedDB now accessible from worker threads.

HTML5: OpenH264 support added to WebRTC for Android.

HTML5: New SDP/JSEP implementation in WebRTC.

Firefox 37 was supposed to arrive faster than usual (“by the end of March”), and indeed it has made it in the nick of time. Mozilla typically releases new Firefox versions every six weeks, and we thus expect Firefox 38 to arrive in mid-May.