There must have been some sort of IP-range block. Usually, it’s site-wide but perhaps it can be enabled for individual models on that site (or the CDN where the video file is hosted)?
The weird thing, which I forgot to say above, is that I was able to play their videos 3 days ago but not when I checked again, after alien 007’s post.
But now they are playing for me again in both Firefox and Brave.