@babaroga: Hello there,
The button will not show up if you use the above CSS Code. It is not possible to have both sound on the video and autoplay. The free version has the video sound feature so the video won’t autoplay. The pro version has the toggle option to enable sound and autoplay. So the button is needed as when the sound is enabled the video won’t autoplay.
Is the video showing up well on mobile devices now? Are you still having any issues?