This happened to me last week. I wasn't streaming or anything, but I was playing Dirt Rally. It was an online stage, which you only get one shot at per day. 30 seconds in, W10 decides it needs to do some upgrading right then, so it collapses my game into a window, throws crap all over the screen and forces a restart. Afterwards, due to Dirt Rally policy of disallowing a stage restart if the game is exited mid-stage, I was unable to have another shot at it. In the overall scheme of things it matters very little, but I was absolutely blown away by the sheer chutzpah of the OS doing that.
I'm a Mac guy, and only use W10 to run this game - it's nothing but a launcher as far as I'm concerned. Macs may be many things (and a great gaming platform isn't one of them, hence I have a PC for that), but I can't imagine a Mac ever doing something this obnoxious. If they ever do, that's the end of me upgrading for sure.
If anyone knows how I can disable this I'm all ears. I have everything else disabled that I can see - location, Cortana, etc, etc, but it STILL thinks it knows better.