The teaser looks like it has been specially created as a teaser and is not a cut-out scene from the show (from what it looks like). The video features three Starks -- Arya, Sansa and Jon Snow. They are seen walking down the famous dark alley at their home Winterfell. As they walk, they are haunted by the memories of their dead parents, Ned and Catelyn Stark. See the first glimpse of the final season.
The first to walk, Jon Snow hears his dead father’s voice telling him: You are a Stark. You might not have my name, but you have my blood.” Sansa and Arya also some hear some voices. As the trio visualise their own statues in the tunnel, the warm visuals give way to icy blue tones. See first look here.