The quarterfinals of the Intel Extreme Master Pyeongchang are live at this moment, with the semifinals and final match being played tomorrow. This is an special tournament because is the first time a E-Sport is getting the support of the International Olympic Commite. The casting is newb friendly, so even if it your first time watching professional, they will guide throughout the games.
I am not sure if posting direct links are allowed, but you can watch the stream on the ESL Starcraft 2 Twitch channel.