We have a security protection in place that requires a browser cookie to be set before login is allowed. This cookie is generated by any visit to a regular Commons page. If the browser doesn't have this cookie, the login request is rejected with a 401 error.
Something like this appears to be happening with webrecorder.io, though I'm unsure exactly what the details are. When I try to use the native browser recording, I can't actually load any pages at all; it appears that there's something about the way that the Commons redirects work that, in conjunction with my browser settings, breaks page loading. When I use webrecorder.io's remote browsing tools, login cookies seem to be set correctly.
Without knowing more about how webrecorder.io works, I'm afraid there's not much more that I can do.
A word of caution to the reporter. This is the first I've heard of webrecorder.io, and it sounds like a cool and legitimate project. But you should be extremely wary of entering username/password credentials into any system that processes them remotely. This goes for the "native" browser session recording (which appears to include a keylogger) and especially the "remote" tools, where they could be harvesting everything that you enter into the window. They probably aren't doing anything nefarious, but it would be very easy to do so.
