Pass pluginPath to MediaElement.js, fixing playback when ME.js is served through load-scripts.php.

props ocean90, wonderboymusic, azaozz.
fixes #24902.



git-svn-id: http://core.svn.wordpress.org/trunk@24940 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Update about page for new screenshot and new video encoding. Remove old screenshots directory. fixes #24832.



git-svn-id: http://core.svn.wordpress.org/trunk@24942 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Use wp_get_mime_types() when calling wp_check_filetype() in the audio and video shortcodes. fixes #24911.



git-svn-id: http://core.svn.wordpress.org/trunk@24944 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Update MediaElement.js to 2.13.0 build, which fixes issues WordPress reported. see #24183.



git-svn-id: http://core.svn.wordpress.org/trunk@24946 1a063a9b-81f0-0310-95a4-ce76da25c4cd