I have rendered a twig page from the Controller, in Sonata, and I have the video in it. The video does not play and I get the error in Firefox 'No video with supported format and MIME type found'.
I put the video tag in a dummy html page and it's fine.
<video width="400" controls>
<source src="/store/tvdelivery.ro/media/preview/3cefd43df26316158e48359155b4cdeae3ba3e7c.mp4" type="video/mp4">
</video>
</div>