Jemm, speaking for Screenhero, we take your concerns seriously (many certainly share them), so don't freak out just yet! We're trying to think of the right pricing scheme that doesn't scare off our individual users, and we are certainly open to feedback and suggestions on this front.
Does Screenhero perform a peer to peer connection or is there a relay server in the middle the whole time? I imagine a relay server would necessitate a subscription to keep the lights on.
We use a peer-to-peer connection for the streaming video, but most of the rest is mediated by our servers. And future fancy features will require additional server resources, including video transcoding. So you are right, this is exactly why we are pursuing a subscription model.
Same here, if they were ever to charge monthly, I'd stop using them immediately. It's a great service, but not that compelling that I wouldn't switch to other cheaper alternatives.