Hello,
since the upgrade to 6.3 Firefox on Linux(ESR and 59) can’t play videos on the WebUI, I always get The media could not be loaded, either because the server failed or because the format is not supported.
On chromium-based browsers everything works. I think it’s someathing with react.js or jquery, but I don’t found a solution yet. Firefox on Windows works.
Edit: Deleted unrelated log output