On a page such as http://en.wikipedia.beta.wmflabs.org/wiki/Media_Interface_VisualEditor_Test?veaction=edit
Click Insert/Media
Note that the default text in the search box is the title of the page.
Click inside the search box.
Default text should disappear but does not. RETURN also does not remove the default text.
Compare to the Link interface which looks similar but behaves correctly.