I will say this... It was a little confusing the first time I did it. I think this was: that it popped up the browser window in an existing browser session I had running (a new tab in Firefox), but didn't restore the window, which I had minimized, so it just looked like MC wasn't doing anything. However, I don't remember it very clearly.
Once I figured it out and authorized MC via Twitter this one time, it worked fine.