How to publish .php page instead of .html at github to demo some php content?

I am looking at the following demo - http://blueimp.github.com/jQuery-File-Upload/

To my understanding in the demo, php files are being served from github which means php content can be served / run from github.

I understand the process to publish html content from code hosted at github via this link -
http://help.github.com/pages/

I am just curious to know how can I show a .php page as a demo, similar to what is done in blueimp above.

I tried similar thing at http://synechron.github.com/index2.php
but instead of displaying in the browser window the page gets downloaded in Google chrome and in IE9 index.html is displayed.

Thanks in advance !!

Github Pages is not a full-featured web host. It will not execute PHP, or any other arbitrary code.

No, you can’t.

Github Pages let you serve web client content (HTML, Javascript, CSS) without the need of owning and maintaining a web server. You can make sub folders, map your domain into it. Use tools such as Jekyll or Hugo with some basic programming skills, you can make your site work as good as an CMS.

However, it does not allow you to use any backend technology to process and manipulate data/logic.

So, PHP is not possible.