If users have an active cable or satellite TV subscription, they will now be able to log in to the NBC Sports Live Extra app on their Apple TV to start streaming live sports aired by NBC's channel roster—just in time for the rest of the Stanley Cup Playoffs. From NBC:

In addition to the Stanley Cup Playoffs and Triple Crown, Live Extra streams all live sports content televised by NBC, NBCSN and Golf Channel, including: the Summer and Winter Olympics; Sunday Night Football and NBC's NFL pre-season and post-season coverage; NHL regular-season games; the PGA TOUR, including the FedExCup Playoffs, and the LPGA; the Premier League; studio content surrounding many of the aforementioned properties; original programming such as The Dan Patrick Show and Men In Blazers; and much more.

Some content, such as game highlights, is available without a subscriptions. However, as stated above, users will need an active TV subscription to log in and stream full games.

Source: NBC