This is a video taken by passengers of the inside of a car running on the Tohoku Shinkansen immediately after the earthquake.
In the video, the lights inside the car other than the emergency lights are off, and an announcement is being made saying, "We are currently out of power due to the earthquake. We will inform you as soon as more information is available."
According to the 25-year-old man who took the picture, the Shinkansen was on the way from Omiya to Utsunomiya, and he felt the shaking of the earthquake immediately after the lights in the car went out.
The man said, "I was surprised because the lights suddenly went out. The shaking didn't feel so big and the passengers in the car were calm."