Video thumb no longer displayed in WYSIWYG editor (via Media).

With the current dev version, a red outlined box with the label "iframe" is displayed in the WYSIWYG editor (while editing). Rolling back to the RC2 fixes this in that the video thumbnail is displayed instead.

media 7.x-2.0-alpha3+34-dev
ckeditor 4.3.1.3ecd0b8