Firefox now supports AV1, a next-generation video codec, on all major desktop platforms. Also, playback on those platforms is now powered by dav1d, a faster and more efficient AV1 decoder developed by the VideoLAN and FFmpeg communities.

https://blog.mozilla.org/blog/2019/05/21/latest-firefox-release-is-faster-than-ever/ https://hacks.mozilla.org/2019/05/firefox-67-dark-mode-css-webrender/ https://hacks.mozilla.org/2019/05/firefox-brings-you-smooth-video-playback-with-the-worlds-fastest-av1-decoder/