Wordpress 3.9 beta 2 is now available for download and testing.What’s new in this beta?
Rendering of embedded audio and video players directly in the visual editor.
Visual and functional improvements to the editor, the media manager, and theme installer.
Various bug fixes to TinyMCE, the software behind the visual editor.
Lots of fixes to widget management in the theme customizer.
Download WordPress 3.9 Beta 2