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.
1 To treat motion sickness in a car, seat your child so he or she faces the front windshield (watching fast movement out the side windows can make the nausea worse). Also, reading or playing video games in the car could cause motion sickness.  Don't let kids eat and play at the same time.