Forgot to attach the Videos:

Hi Antauris,

I was able to reproduce the issue but there is nothing we can do.
As you said in your comment, it is simply an issue with the video file itself (the way it was created/compiled, its settings, codec, etc.)

The video file cannot be played on its own as well (out of the website/template/particle). Here, have a look at this video, it shows what I mean.

Just see what is different between the working and the not working video file. Make sure you compile/record/save the not working video with the same settings as the working one. You might also want to Google the error message and see what comes up (No video with supported format and mime type found).

Thank you for your advice. I guess i'll try to rerender or rerecord the damaged ones. What confuses me is just that all videos are working fine when played in an usual video Player like VLC media Player.

No problem mate.
Yeah, I really don't know what to say. It is definitely an issue with the video file itself but what exactly the issue is I just cannot say.

Thank you for the update Antauris.
I'm glad you figured it out