Is is a valid URL.Ideally would need the full, correct URL.
It was a live video - prior to going live. It shows correctly now after going live. The bug is scheduled live video posts fail to render even though such posts render just fine in Facbook itself.I think the report may specifically be related to a live video, perhaps while it is live. Or perhaps it was a temporary bug.
When I replied, the video wasn't loading in any browser. So there's some weirdness here but the report wasn't specific to Firefox so your issue is likely different.