Make the About video responsive.

fixes #24832 for trunk.

git-svn-id: http://core.svn.wordpress.org/trunk@24952 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Compress scripts/styles: 3.7-alpha-24954.

git-svn-id: http://core.svn.wordpress.org/trunk@24954 1a063a9b-81f0-0310-95a4-ce76da25c4cd