Yes, it works fine in Google Chrome 70, Chromium 68 and Firefox 63.0.1, so the issue is most likely on your side.
Claes
3
@foto: might you perhaps be on Windows something?
Have fun!
Claes in Lund, Sweden
Claes
4
… and works fine using Microsoft Edge as well as Firefox 63.0.3 on Win X 64-b.
foto
(Syv)
5
Manjaro/archlinux Firefox 63, xfce desktop
Thanks
Syv
Claes
6
Peculiar!
I am on the same Manjaro/XFCE and use ffox 63.0.1 64-bit.
And the vid works fine here!
PS: I have a faint memory of having OK:ed extra video encryptations or something similar when installing Manjaro
Claes
7
@foto open your program manager, search for mime. I have these four enabled: 
foto
(Syv)
8
Here are mine:
perl-file-mimeinfo: 0.29-1
shared-mime-info: 1.10-1
mailcap: 2.1.48+14+g5811758-1
perl: 5.28.0-1
Thanks
Syv
Claes
9
Hm. Next wild guess. In the pgm mgr, search for codec.
Here are mine:

Claes
10
Here is what the video in question needs:

Firefox should have its own, internal h264 decoder.
afre
(Alan)
12
@foto It is quite possible that your Firefox settings or plugins are interfering. I have experienced the same thing before.