Facebook Videos and Firefox 52.9 ESR

I've just made the rather annoying discovery that the new Facebook layout, which will become mandatory next month, apparently causes the playing of videos to break if Firefox 52.9 ESR is used with the Primetime plugin. The videos appear for an instant, and then go to a black screen with a message on it saying that the video can't be played.
Reverting back to the old layout makes it all come good again.
Can anyone else confirm this?