That's the road that goes over Hellisheiði between Reykjavík and Hveragerði/Selfoss. If you look up Dalakot (the white building with red roof in the video) or Hellisheiði power station on Google maps you can see where that stretch is.
It's always steaming a certain amount there - hence the power station, tons of geothermal power available. Interesting if things are shifting around there somehow.