here is the vimeo player embedded in a GH Pages site
<iframe src="https://vimeo.com/event/1327537/embed/d8817e8277" frameborder="0" allow="autoplay; fullscreen; picture-in-picture" allowfullscreen style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe>
Brightcove stream:
<iframe src="https://players.brightcove.net/6314018604001/4SNdO9Lix_default/index.html?videoId=6322680080112" allowfullscreen="" allow="encrypted-media" width="560" height="315"></iframe>and here is a sample unlisted yt video
<iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/GTVn67sdmvA?&modestbranding=1&rel=0&showinfo=0" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>Having trouble with Pages? Check out our documentation or contact support and we’ll help you sort it out.