Rated 3 out of 5 stars
But why it doesn't work with https://login.live.com ?This review is for a previous version of the add-on (2.2.5). This user has a previous review of this add-on.
Unfortunately, the login form on that page is built completely through scripts, after the browser's autofill has already checked for login forms, and at that point it is too late to convince it to do anything. I cannot do anything about it in SPE, short of turning SPE into a full-fledged password manager in its own right, which I will not do.
It might be possible to work around the problem by using, say, a user script (see the Greasemonkey add-on) to build a substitute login form in time for it to be picked up by autofill. The trouble is that I have no idea what all of those scripts are doing (maybe they don't actually affect how it's submitted, but I'm not sure), and I do not have a Windows Live account, so *if* I were to write a user script, I would need someone who does have an account to help out, for instance by testing. The easiest thing would probably be if I got a trace showing how the form actually gets submitted (with the username, password, etc., censored, of course).
Alternatively, people could convince Microsoft to make the form password manager-friendly, but somehow I don't see that happening: they might well want things this way. Until something like one of the above happens, there's no way anyone will get their password autofilled on that page with the built-in password manager. Sorry.
EDIT: I think a good bet is iMacros for Firefox.