Viddler has had a new oEmbed endpoint for at least 10 months. Let us update to it.

Props garhdez.
Fixes #24296.

Built from https://develop.svn.wordpress.org/trunk@28556


git-svn-id: http://core.svn.wordpress.org/trunk@28382 1a063a9b-81f0-0310-95a4-ce76da25c4cd