You cannot use view source to view PHP source code...that only works with HTML. If you do view source it will just show what was outputed.
example...think of a really cheap calculater, you do the math problem 2 + 2...and when you put that in what you see is 4, you don't see 2+2.
The same apply's to php, you see what the result is but you cannot see how they got there.
Best bet would to ask the webmaster of that site.
[edit]or just check out hotscripts.com[/edit]