This should've been fixed in the latest, I think Mozilla pushed it, try manually checking for updates or pull it from the github page.
The issue was caused by a fix I put for Bluetooth for someone else, where his headphones werent resting when a video was paused.
So I started force stopping the audio hook when stream was off, but that caused as you see some pages not rehooking.
Again it should be fixed in 6.7; which again is available in the github, but may be waiting for approval from mozilla.
If its not fixed in 6.7 lmk in the github.