It is against vBulletin's licence agreement to distribute vB files. This means if anyone did have a fully commented one they wouldn't be able to send it to you as it violates the licence agreement. This is also one of the reasons full vB files are not allowed to be posted here.
@NTLDR:
Fair point.
Would it be an option to just make it available to licensed customers? I'm not thinking of anything like redistributing, it's merely an idea to support the developer community. I sometime wonder what's going on in these files, eventhough I do have a solid understanding of PHP.