Steam Videos will not play in Firefox Browser?

[Chaostraveler]

Just for grins I tried to stream the copies of the Ace Attorney anime that I bought years ago and I was surprised to see it open up in Firefox. I was then disappointed and confused when the screen stayed black and said "You must update your version of the Steam client to watch this video."

I tried looking through the linked FAQ but nothing listed mentioned updating anything, let alone watching in a web browser. Just in case I tried coping the link for the video to Chrome and it magically worked. I've disabled my uBlock Origin for the page in Firefox and had disabled some other extensions because Youtube was being stupid with them but I've no clue why simply changing browsers will let me watch this.

Any ideas would be great as I kinda want to purge Chrome if I can, but otherwise is there a launch option I can add to the video to make it open in Chrome or another browser?