Support for ffmpeg8

[tabascosw]

Currently waterfox does not support ffmpeg8, on some webpages like ESPN, kicker, etc, videos won't play or videos without sound. I have to re-add ffmpeg7 to make it work again.
This bug is also present in firefox esr and has been patched. https://bugzilla.mozilla.org/show_bug.cgi?id=1962139
Would be nice to get that fixed in waterfox as well.

[SametAylak]

I think this is really urgent. It's terrible without a proper ffmpeg support.