In `WPPlaylistView::ended()`, at the end of a playlist, set the index to `0` and call `->setCurrent()` instead of `->loadCurrent()` so that the first track is properly highlighted.

Fixes #28428.

Built from https://develop.svn.wordpress.org/trunk@28649


git-svn-id: http://core.svn.wordpress.org/trunk@28467 1a063a9b-81f0-0310-95a4-ce76da25c4cd
In the spirit of [27622], add a few CSS rules to ensure that videos will be responsive, regardless of theme.

Props Funkatronic.
Fixes #28414.

Built from https://develop.svn.wordpress.org/trunk@28650


git-svn-id: http://core.svn.wordpress.org/trunk@28468 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Add oEmbed support for TED talks.

props pdclark.
fixes #28285.
Built from https://develop.svn.wordpress.org/trunk@28651


git-svn-id: http://core.svn.wordpress.org/trunk@28469 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Because of YouTube's overwhelming dominance in the online video space, we should help our users who paste bad URLs when possible. It is easy to fix `http://youtube.com/embed/acb1233` URLs by turning them into `http://youtube.com/watch?v=abc1233` embeds using an embed handler (we already have one to fix Google Video embeds).

We should avoid doing this in almost every other case, but it's YouTube, and it's an easy error for a novice to make.

Fixes #24660.

Built from https://develop.svn.wordpress.org/trunk@28652


git-svn-id: http://core.svn.wordpress.org/trunk@28470 1a063a9b-81f0-0310-95a4-ce76da25c4cd