Just had a thought. How difficult would it be to implement a little flag on games, where the creator can invite (or disinvite) streamers to stream their creations? I think this would be an especially wonderful add for Game Jams.
there be custom tags. you could tag your stuff with streaming-allowed or some such already. but who would search for it... existence of custom tags is not really well known. you could click on the streaming-allowed tag on other games to go to your game that is tagged the same. currently i am not aware of any streaming invitation tags. maybe you will start making it popular :-)
but even with tag, you should have it in description.