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.
It doesn't cause long-term problems, but it can make your life miserable, especially if you travel a lot. Children from 5 to 12 years old, women, and older adults get motion sickness more than others do.