Hi I’m oneboxing Twitter feeds and all is well except for Firefox which won’t show the video.
I get a mime type error placeholder.
I double checked here on Meta and found this post.
https://meta.discourse.org/t/how-to-embed-a-video-from-twitter/142685
This screenshot is from that thread using latest Firefox, no extensions, plus only two plugins which came installed.
It’s working in Chrome and Edge.