I was pretty confused as well. The game has it's similarities with Twitch Plays Pokemon (hopefully without as much heartache, RIP Moon Stone) but with less confusion. The idea is that you watch a match live, viewers then make decisions and every five seconds a move is made. You can see it live here.
This is a pretty good idea, unlike Twitch Plays Pokemon this will have
some educational benefits. Everyone and their dog knows what Pokemon is
and has probably played it at some point in their life. With
Hearthstone, fewer people have played it and even fewer can play it
well. I love Hearthstone ever since I picked it up not long ago but I
need some advice on how I should play and what decks are strong against
what else. I am nowhere near the level I want to be but hopefully
watching what other people do live can help me get there. Or maybe it will
descend into chaos and I won't learn a damn thing.