3D FlipBook - Wordpress - Embedded Video does not run with Firefox

Dear 3D Flipbook Team, first of all: 3D Flipbook is simply great! Many thanks for this wonderful tool :-)

If we run the embedded video with Firefox, it does not run (picture of the video looks blurred, no controls visible). With all other browsers it works.

Also this example has the same problem on Firefox:

https://3dflipbook.net/embedded-video

Many thanks and best regards, Ben