Quote:Mozilla released Firefox 64.0.2 to the stable channel on January 9, 2019. The new version is a bug fix release that addresses several issues of the previous version of Firefox including a video stuttering issue on YouTube and a crash fix on Mac OS X devices running Firefox.

Mozilla released Firefox 64.0. in December, and Firefox 64.0.1 for Android exclusively (Firefox 64.0 was not released for Android).

The new version is already picked up by Firefox's automatic updating functionality; users can verify the version by selecting Menu > Help > About Firefox from the menu. An option to run a manual update check may be provided as well depending on how updating settings are configured.

Firefox 64.0.2 can be downloaded from Mozilla directly as well; either to install the browser over an existing installation or install it as a new program on the device.

Firefox users noticed micro-stutters on YouTube when playing videos after the upgrade to Firefox 64 even with the video quality set to Auto and on relatively powerful machines where this should not happen. The issue affected Firefox on all supported operating systems (desktop) but not other browsers that users ran on their devices.

Full reading: https://www.ghacks.net/2019/01/10/firefox-64-0-2-fixes-video-stuttering-on-youtube/