I am currently using the following video code on our website resp. landing page:
<div style="position: relative; display: block; max-width: 960px;"><div style="padding-top: 56.25%;">
<iframe src="<VIDEOSOURCE>" allowfullscreen=""
webkitallowfullscreen=""
mozallowfullscreen=""
allow="encrypted-media"
style="position: absolute; top: 0px; right: 0px; bottom: 0px; left: 0px; width: 100%; height: 100%;">
</iframe></div></div>
If I call up this page directly, I can open the video in full screen. I set up a subdomain which redirects to this landing page with masking. Page 1012312.system.com becomes start.company.com.
The problem now: If a visitor accesses the page via the subdomain resp. forwarding with masking, the video cannot be played in full screen anymore.