You cannot watch Facebook livestreams without disabling the anti-track function. One of the biggest concerns with Facebook streaming has been the sharing of Data with Facebook, one of the companies notorious for keeping customers data and selling it to advertisers. The Dota2 community has been extremely vocal about their disdain for Facebook as the exclusive streaming platform.
I think you have to disable the anti-track function, then it should work.
— Ulrich Schulze (@theflyingdj) January 24, 2018