For CSS demos, I suggest using http://dabblet.com which will automatically add vendor-prefixes. In this case it might not have helped due to the appearance property (which was dropped from the CSS spec [1]), but often only webkit prefixes are used even if properties are supported in other browsers.
This won't actually work in any other engine except for webkit, even if you vendor-prefix the rules. This is because he is using an :after pseudo element on a checkbox, which shouldn't work and is technically a bug in webkit (according to the specifications, you cannot use :before/:after on replaced elements).
Oh, didn't notice that. The specification actually does not explicitly prohibit pseudo content on replaced elements.
This specification does not fully define the interaction of :before and :after with replaced elements (such as IMG in HTML). This will be defined in more detail in a future specification.
1: http://wiki.csswg.org/spec/css4-ui#dropped-css3-features