Solved Firefox 149 on FreeBSD 15 – YouTube videos not playing ("Unable to play this video")

Hi,

After upgrading to Firefox 149.0,2 on FreeBSD 15, YouTube videos no longer play.
Symptoms:

YouTube displays: "Unable to play this video"
Issue occurs on all videos tested
No playback starts at all

Environment:

FreeBSD 15.0
firefox-149.0,2 (installed Mar 22, 2026)
Installed via pkg (quarterly repo)

What works:

Same videos play fine in Chromium
System video/audio stack appears OK

What I tested:

New Firefox profile → same issue
Firefox safe-mode (no extensions) → same issue
Codecs show as supported (H264, VP9, AV1, etc. in about)
Disabled hardware decoding → no change
Disabled RDD sandbox → no change
media.mediasource.enabled = true
media.eme.enabled = true

Additional info:

Video playback was working fine before upgrading (likely Firefox 148.x)
Issue appeared immediately after upgrade to 149

Conclusion:
This looks like a regression in Firefox 149 on FreeBSD affecting YouTube playback (possibly MSE or networking pipeline).

Is anyone else seeing this?

Thanks
 
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