Implement video autoplay for Plus with option to disable

For Pro and plus customers:

• the top video should begin playing when it's in the view port.
• Only one video should be playing at a time (this should be handled by the plyr instances)
• The video should be playing muted (@markeharding 's request)
• The video should unmute when clicked
• Scrolling out of the view port should stop the video
• The video should resume playpack with audio in the modal pager / media modal when viewing the video in a single entity view