Final about page for 4.0. Enjoy the videos!

props ryelle, melchoyce, smashcut, wonderboymusic, helen.
fixes #29494.

Built from https://develop.svn.wordpress.org/trunk@29706


git-svn-id: http://core.svn.wordpress.org/trunk@29480 1a063a9b-81f0-0310-95a4-ce76da25c4cd