All demonstrations are based on the same example, which you can call here.
By a click on the green text "Please click here" you will in fact click on the submit buttom of target.html.
In the second demo, which you can call here, a frame buster in the target page prevents the attack. When the page target.html should be loaded in the iframe, the frame buster assures the page is loaded in the main window instead and thus replaces the attacking page.
In the third demo, which you can call here, the sandbox attribute for the iframe prevents the execution of the frame buster, thus the attack is possible again.
The third demo didn't work for you? Then you uses the "wrong" browser, as so often with HTML5. The third demo was successfully tested in Chrome, Safari and iCab (a browser for Mac OS X which bases on Webkit).
Firefox, Internet Explorer below version 10 and Opera don't implement the sandbox for iframes, thus the demo (and clickjacking attacks based on the use of the sandbox) don't work.