Except I have Click to Flash installed in Safari, and it still insists on that full screen flash monstrosity.
In other words, you will always see that gray 'Flash' box with ClickToFlash instead of getting any no-flash fallback content that may be setup.
Unfortunately I don't think there is an easy way to temporarily and completely disable Flash in Safari for sans-Flash testing.
Prefs -> Security -> Uncheck "Enable Plugins", refresh.