It's odd because in my dev environment with the web server running on my laptop Alby doesn't work. It throws an error when I try to use it. But Nos2x works fine. But on the public web server Alby works just fine and I've had a few people say Nos2x doesn't work for them. I'm not sure what's different since all the extension is doing is injecting code onto the page to provide access to an object on the window. It's not complicated, so I'm not sure why it's so finicky.
Discussion
Interesting. You're probably better sandboxed. I have other extensions running and maybe one of these is causing a conflict