The section of road shown in the video is the I-5 express lane where it rejoins the regular freeway in North Seattle: https://www.google.com/maps/@47.7021836,-122.3299637,3a,71.1... Note how it's configured for southbound traffic in the street view image. It switches direction twice a day.

Though you can't see it very well in the video, there is a crash arresting net after all the signs. https://www.google.com/maps/@47.7034263,-122.3302029,3a,19.3... You can't just drive through a couple of boards and run into oncoming traffic.