There seems to be a problem (across several platforms, but mainly Firefox) with recognizing the exact file format if the link is directly pointing to the mp4 file instead of having the video embedded on a page. Try saving the link as file and watch it from there.
PS: And as a test. Does this work? It’s the same link, but now obviously here inside the page.
“No video with supported format and MIME type found” on MacOS Firefox.
There seems to be a problem (across several platforms, but mainly Firefox) with recognizing the exact file format if the link is directly pointing to the mp4 file instead of having the video embedded on a page. Try saving the link as file and watch it from there.
PS: And as a test. Does this work? It’s the same link, but now obviously here inside the page.
Main submission works fine for me on Firefox, Linux.