Some edits will only show when logged in. On the link provided (http://en.wikipedia.org/wiki/Xtreme_Radio), I have edited the page (as icecold), but if you access the page from a fresh browser (clear cache, cookies and not logged in) the edits will now show. If you then click on the history page it will show the edits and will let you compare, and therefore see the page as it should be.
How to reproduce:
Clear the cache and cookies.
Log in, and access the page again.
You will find an image has appeared and other edits. This is what should appear the first time.
Clear cache and cookies.
Access (http://en.wikipedia.org/w/index.php?title=Swansea_University_Students%27_Union&diff=185145573&oldid=184961086) - Which is the history link.
See the edits appear.
Hope this is enough information for you.