I can't actually watch/favourite, it gives me the "need to be logged in" error, but then redirects me to a 404. This forum doesn't have watch as a guest, but yours does, not sure if it's an ACP setting, but I don't recall seeing it. I've got a few bugs I've spotted whilst using my iPad that I'm going to put onto GitHub, but I'll do some more testing later into guest permissions.
Edit:sorry, when I said replying and voting are fine, I meant they don't redirect, I can't actually reply or vote. 😄 I need sleep.
Hmm, interestingly enough, it works on my site, you'll need to take everything in //convoe.com/vendor/convoe/_cnvo.register.js and make your own file and replace it, you don't really have to remove it completely. This is because I have hot-linking blocked as far as assets goes.