I do not think the government is behind the video, but rather come conspiracy theorist group. I spend t many years in Emergency Services, and was a fire department officer, paramedic, instructor and member of the local advisory council. We participated in drills on a regular basis. When planning one we always looked for ways to make it as bad as possible. We went for worse case scenarios, as realistic as possible and threw every sort of twist in that we. The National Training Center actually has simulated collapsed buildings, caved in tunnels, simulated interstates they can set up massive simulated crashes and fires, and more.
When I was Captain of Rescue, we had a great example of why you do things that way. We got a call from the airport, a large plane was declaring an in-flight emergency. Communications were an issue but we knew the aircraft type could hold up to 130 people, way bigger than our little local airport was equipped to handle. The plane managed to land safely, and though it ended up in the sand at the end of the runway because it could not stop fast enough on our runway with an engine out, no one was hurt.
However because of the drills we had conducted with the airport, we know what equipment we needed, who we needed to call in for mutual aid, and where we needed to position our equipment. Everything went like clock work because we "planned for the worst and hopped for the best." That is all they are doing here, Tsunamis happen, and they happen not infrequently, so wisdom dictates that if you live in a Tsunami prone area, you practice for the day it will happen. Notice I did not say if it happens, because like the plane that was too big for our little commuter airport, it WILL happen.