* Playlists operate like galleries in the admin.
* Provide default UI and JS support in themes using MediaElement and Backbone.
* The shortcodes are clickable, editable, and configurable using the media modal.
* Playlists support images for each item, whether or not the current theme supports images for `attachment:audio` and `attachment:video`
* Playlists respond to `$content_width` and resize videos accordingly.
* All playlist data is included inline, using a script tag with `type="application/json"`, allowing anyone to unenqueue the WP playlist JS and roll their own.
* Playlist styles are minimal and work out of the box in the last 5 default themes. They inherit and adapt to the current theme's font styles, and their rules are easily overrideable.
See #26631.
git-svn-id: https://develop.svn.wordpress.org/trunk@27239 602fd350-edb4-49c9-b593-d223f7449a82
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