In Chrome 33.0 (recently released) they've got a bug that affects the visibility of flash elements.
With the Flash uploader, the icon is hidden using visibility:hidden - in recent Chrome updates this is not sufficient to hide it & it is always visible in the centre of the page (see the attached screenshot.)
Note: This requires a specific Chrome version (33, which as of 24-FEB-14 is the latest) and does not occur on other browsers, but occurs on both Windows and Mac OSs.
A bug was raised a month ago with Google regarding Chrome's behaviour but no response has been received. This issue still exists in Chrome Canary, so no fix is in the visible pipeline.