Don't hardcode `height` for videos - this was a workaround for MediaElement internals causing problems. Responsive videos now work properly and don't cause extra whitespace.

Fixes MediaElement by hand in the interim: https://github.com/johndyer/mediaelement/pull/1337
Video playlists were completely broken by this.

Fixes #30078.



git-svn-id: https://develop.svn.wordpress.org/trunk@30082 602fd350-edb4-49c9-b593-d223f7449a82
Allow developers to override the `settings.success` callback for MediaElement players.

Props nofearinc.
Fixes #30029.


git-svn-id: https://develop.svn.wordpress.org/trunk@30083 602fd350-edb4-49c9-b593-d223f7449a82