When approving a post that system thinks should not have you are presented with something along the lines of
This post has severe quality issues. It is abusive nonsense, noise, spam, blatantly off-topic or otherwise irredeemable - readers will find it offensive or repulsive rather than helpful. You should delete or recommend deletion when reviewing such posts.
Don't worry, we've already handled this post appropriately - but please take a minute to look it over closely, keeping in mind the guidance shown above.
With a "I understand" button, what about if you disagree with that assertion? Is there a way to indicate that? If there isn't perhaps one should be added so that data can be collected to improve the system.
Try s3auth.com (I'm a developer). It does exactly what you're looking for, free of charge.
Which I approved and the system responded that I should have recommended deletion.
From what it looks like to me the OP is asking a question about adding basic username/password authentication for an Amazon s3 hosted website and the answer is mentioning a free product/service that does what the user wants. It is true that the user answering is affiliated (they posted a disclaimer) with the product but from what I understand that is allowed.