Driving fast is easy once you get used to it, especially on a road as perfect as the German autobahn. I've gone way faster on much worse roads in the middle of nowhere USA. 140 KM/h is not very fast at all. Those bikes are going much faster in the video. The speed limit on the highway in Texas is around 140 KM/h. I've gone 298 KM/h on a sport bike, and 170 KM/h in a car. The car was easy as can be. I do admit that 298 KM/h on a bike was excessive, and scary, and I decided not to do that again. But 193 KM/h was pretty standard for me when I had a sport bike.

Edit: the vehicle you are in makes a big difference. Cars and bikes built for those speeds have tight suspension, and handle well at high speeds. An old beat up Toyota Corolla isn't going to be safe or fun at those kinds of speeds.