Markup: templates/output/04-elements/videos/mp4.html
<video class="video-embed-item lightbox-video-element" width="1200" controls="" id="selector_video">
<source src="https://sample-videos.com/video321/mp4/720/big_buck_bunny_720p_1mb.mp4" type="video/mp4"/>
</video><a class="lightbox lightbox-video" href="#" data-type="html" data-target="#selector_video" data-group="inline_video"><img src="https://placeholder.in2code.de/800x525" width="900" height="600" alt="Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa."/></a>
Source:
assets/sass/04-elements/_elements.videos.scss, line 70