Varies: There is no specific dangerous heart rate during exercise. How fast your heart beats with exercise depends on a number of factors, especially your conditioning. If you are healthy, a heart reate in the 170's or even higher may be ok and tolerated.
Motion sickness caused by video games, sometimes called simulator sickness, is caused when there is a disconnect between what your eyes are seeing and what your body is feeling.
Motion sickness can occur during any type of movement that is unintentional. Car sickness, seasickness, and air sickness are examples of motion sickness. Complex types of movement, especially slow movement or movement in two different directions (such as up and down plus back and forth) at the same time (commonly the movements of a boat in rough water) are most likely to cause motion sickness.