My #1 concern is this:
On Twitch.TV I would never watch someone who is completely quiet. Half the time I have Twitch up as a passive form of entertainment. Similar to a radio talkshow going on in the background.
When I'm developing software... I don't talk. I might do an odd grumble to myself every once in a while, but the loudest thing in the room, by far, is my keyboard.
Are you expecting developers to talk out their thoughts as they type? Are you expecting people to just stare at a quiet developer's workflow and try to glean information?
Also, this comic strip comes to mind: http://www.commitstrip.com/wp-content/uploads/2015/06/Strip-...
TL;DR: Why would I as a developer want to use your service? What do I gain from it?