Firefox freaks out when a site has a self-signed certificate, or if there are any other number of problems or "problems" with a site's certificate. It's behavior is to change the whole page, hide any UI allowing you to proceed, and then if you find the button, it defaults to the worst possible solution: to permanently store an exception to its freaking out. You can read more about the phenomenon in any of these different articles and pages. This is part of the trend to incessintely nag users to death, and the main effect is to train users to click through repeated popups, dialogs, etc without actually investigating.
I did a search looking for about:config settings and extensions to change this behavior, and did not find a way to force Firefox to easily allow you in to a site temporarily.
This article covers an
about:config key, and that does change part of the behavior. If you set it to true, you don't have to search around for the button, it's automatically expanded, and you can just add the exception. Except, more often than not, I don't want to add an exception, I just want to see what's on the other side of this error.
I am looking for an extension, tweak, hack, etc that will change this behavior. Ideally, it would just display the notification bar with something like "Get me out of here!", "Proceed anyways", "Advanced", or similar.
I would prefer this to be free or low cost.
I already run enough security related extensions that I find the built in tools to be getting in the way more often than not. For example, this is probably related in part to HTTPS Everywhere and people testing out certificates.