Video js tweak

Tweaked the video script to avoid duplication of content in html files.

Videos now retain parent <figure> element and are supplied with a <figcaption> taken from the original link text.
Opt-out of this can be done with .no-caption (see index.html)

Also:
• tweaked styles to match changes
• removed extraneous .video class from html
• made the script selector a bit more agnostic