Why do they even need a View Demo button? Almost every article about CSS/JS scripts for cool effects does this, instead of just using whatever they want to demo in the blog post itself.
This way the demo pages are as succinct as possible, the code isn't confusingly intertwined with the html/css/js generated by their CMS (in this case WordPress) and matches as closely as possible what was described in the corresponding article.
It's also a fraction easier (saves finding a per-post css/js plugin), you don't have to worry about wierd interactions with the CMS code, and it will continue to work even if you change the CMS or theme.
