Quote:Mozilla released a new version of its Firefox web browser a moment ago. Firefox 127.0.2 fixes a long-standing playback issue on YouTube that was caused by the Google-owned property and not Firefox according to Mozilla's analysis of the issue.

For the past five or so months, some Firefox users were running into roadblocks regularly on YouTube. The full number of affected users is unclear. We published an article about the issue just last week.

Here are the details:

• It affected regular and live videos on YouTube, but not all of them.
  
• vp9 videos with a resolution of 1080 or higher were affected only.
  
• Affected users noticed an endless buffering issue.
  

Mozilla kept track of two main bugs. These were bug 1900191, which dealt with the live video problem, and bug 1878510, which dealt with the problem when watching regular videos on YouTube.



It took Mozilla some time to analyze the issue and come up with a solution. Core reasons for that were that the engineers could not replicate it at first, even when accessing the same videos on YouTube.

After a while, Mozilla engineer Alastor Wu discovered the root cause of the issue. He said that the issue has been caused by bad muxed VP9 bytestreams served by YouTube. The issue was caused by Google-owned YouTube therefore according to Mozilla and not a bug in the Firefox web browser itself.
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