Update HTML classes in the audio and video shortcodes. props rfair404. fixes #24820.

Merges [24857] to the 3.6 branch.



git-svn-id: https://core.svn.wordpress.org/branches/3.6@24858 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Change 'Change two revisions' to 'Compare any two revisions' for clarity. props siobhan. see #24804.

Merges [24859] to the 3.6 branch.



git-svn-id: https://core.svn.wordpress.org/branches/3.6@24860 1a063a9b-81f0-0310-95a4-ce76da25c4cd