What is this simulator like device called?
Rollers. You have three drums, two at the back, one at the front and the front roller is powered by one of the back rollers. You can also get add ons to give you a breeze:



Balance is what is needed to stay on the rollers, also a wall (as per featured video) comes in handy.

Rollers are used for training purposes although they can also be used for demonstrations at trade shows etc. When riding rollers instead of an exercise bike you do need to balance as well as push the pedals, you can therefore improve your riding, not just your strength/endurance.