add possibility to include embedded videos in webpage paper

[katjaq]

It would be great to be able to include videos in the web paper :)
You mentioned that it would be possible to add an optional video_url in the frontmatter. So that would be great :) Probably along with a comment that videos need to be uploaded to services that allow streaming, such as YouTube, Vimeo, and Youku.

Also in the paper pdf this could maybe be rendered as an image (for example the frame which appears as video preview?) If possible and not too much work.

I will link this issue in the doc repo and note that some doc may be included on the possibility to include video once this issue will be closed \ö/

Thank so much! 🚀