I have trouble. When I try to play YouTube videos, they play super fast. I'd include a video of the problem but it would be too large. Suffice it to say that a 24 minute video finishes in less than 5 seconds when I hit the Play button. This is new with Big Sur. I just installed beta 9 last night. I have turned off all extensions, deleted my history, restarted Safari, all to no avail. The problem happens with Chrome too so might be a QuickTime problem or something underlying.
YouTube videos play back at unwatchably fast rate with Safari on the latest Big Sur beta… anyone else
safarivideoyoutube
Related Solutions
If you don't have Adobe Flash plugin installed you need to do so and give it another go.
Do you have by any chance the Firefox "Flashblock" extension installed?!
Edit: This solution worked only temporarily. In my case, the problem is on-and-off and there is no way to know when it is going to happen.
This exact same thing was happening to me, but in Firefox. This answer from ElementaryOS-SE solved the issue for me. The solution is to basically install the plugin h264ify. From the GitHub page:
By default, YouTube streams VP8/VP9 encoded video. However, this can cause problems with less powerful machines because VP8/VP9 is not typically hardware accelerated. In contrast, H.264 is commonly hardware accelerated by GPUs, which usually means smoother video playback and reduced CPU usage.
Best Answer
This is a commonly reported bug that occurs 'sometimes'. Another solution, short of rebooting, is to kill the coreaudiod process.
You can do this in Activity Monitor, or in the Terminal with
sudo killall coreaudiodhttps://9to5mac.com/2019/07/29/macos-fast-video-playback-bug-fix-coreaudiod-video/