[Dagonfly]

> Please explain how HN is not taking my unlicensed reply and using it in their commercial HTML code sent to your web browser

Nothing unlicensed about your reply. From HN's Terms of Use:

> By uploading any User Content you hereby grant and will grant Y Combinator and its affiliated companies a nonexclusive, worldwide, royalty free, fully paid up, transferable, sublicensable, perpetual, irrevocable license to copy, display, upload, perform, distribute, store, modify and otherwise use your User Content for any Y Combinator-related purpose in any form, medium or technology now known or later developed

[ormaaj]

Yes a standard agreement such as that is expected and customary, and they have it for good reasons. However it is not strictly required in order to make use of user-submitted content.

Also as I have pointed out in other comments, this is a contract, and as such there are quite a few reasons that a contract like this might not be binding. One major weakness is its semblance to a "click through agreement". An agreement hidden in the footer of a website or in the fine print on a registration page is even more subtle than that and it's entirely possible build a case against implicit agreements that automatically kick in through mere use of a web service. There is considerable case law devoted to this and it's gone both ways - depending on the specific facts of the case, who makes the better argument, and the disposition of the judge.