hi, thank you for reporting this. could you please try if you can replicate this behaviour when you launch firefox in safe mode once too?

Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

I was not able to replicate the problem in safe mode.

thank you, is there any change when you perform this?: enter about:config into the firefox address bar (confirm the info message in case it shows up) & search for the preference named media.windows-media-foundation.use-nv12-format. double-click it and change its value to false then restart the browser once.

philipp said

thank you, is there any change when you perform this?: enter about:config into the firefox address bar (confirm the info message in case it shows up) & search for the preference named media.windows-media-foundation.use-nv12-format. double-click it and change its value to false then restart the browser once.

First impression is that it may have fixed the problem but i have to give it some time. This is little bit difficult to reproduce, almost like the browser needs to be under some use before it shows up.

Will report what happens.

thanks, in any case i think it's a problem worthy to file a bug for at bugzilla.mozila.org in case you have the time, so that it gets the attention of mozilla's developers...